From dc14675a1065534213a98a85b446862acbf1b114 Mon Sep 17 00:00:00 2001 From: llj Date: Mon, 25 Mar 2013 20:27:17 +0800 Subject: [PATCH] [markdown] use pagedown for view, edit/preview. * modified Markdown.Editor.js and pagedown.css * offered 'help' popup and 'fenced code block' --- media/css/pagedown.css | 61 + media/css/seahub.css | 16 +- media/img/wmd-buttons.png | Bin 0 -> 7465 bytes media/js/Markdown.Converter.js | 1400 ++++++++++++++++++ media/js/Markdown.Editor.js | 2203 +++++++++++++++++++++++++++++ media/js/Markdown.Extra.js | 593 ++++++++ media/js/Markdown.Sanitizer.js | 108 ++ templates/file_edit.html | 177 ++- templates/view_file_markdown.html | 8 +- 9 files changed, 4518 insertions(+), 48 deletions(-) create mode 100644 media/css/pagedown.css create mode 100644 media/img/wmd-buttons.png create mode 100644 media/js/Markdown.Converter.js create mode 100644 media/js/Markdown.Editor.js create mode 100644 media/js/Markdown.Extra.js create mode 100644 media/js/Markdown.Sanitizer.js diff --git a/media/css/pagedown.css b/media/css/pagedown.css new file mode 100644 index 0000000000..0098898c37 --- /dev/null +++ b/media/css/pagedown.css @@ -0,0 +1,61 @@ +#wmd-button-bar { + height: 20px; + padding:10px 5px 5px; + border-bottom:1px solid #ddd; +} +#wmd-input { + font-family: monospace; + line-height:1.3; + width: 746px; + padding: 4px 5px; + resize:none; + vertical-align:top; + border:0; +} +#wmd-preview { + padding:0; + min-height:600px; +} +.wmd-button-row { + position: relative; +} +.wmd-spacer { + width: 1px; + height: 20px; + margin-left: 14px; + position: absolute; + background-color: Silver; +} +.wmd-button { + width: 20px; + height: 20px; + padding-left: 2px; + padding-right: 3px; + position: absolute; + cursor: pointer; +} +.wmd-button span { + background-image: url(../img/wmd-buttons.png); + background-repeat: no-repeat; + background-position: 0px 0px; + display: inline-block; + width: 20px; + height: 20px; +} +.wmd-spacer1 { + left: 50px; +} +.wmd-spacer2 { + left: 175px; +} +.wmd-spacer3 { + left: 300px; +} +.wmd-prompt-background { + background-color: Black; +} +.wmd-prompt-dialog { + text-align:center; + background-color: #fff; + padding-bottom:5px; +} diff --git a/media/css/seahub.css b/media/css/seahub.css index a36dc17877..b229ee7bd0 100644 --- a/media/css/seahub.css +++ b/media/css/seahub.css @@ -42,7 +42,6 @@ textarea { } input { height:22px; - /*line-height:22px;*/ border: 1px solid #ddd; margin:3px 0; outline:0; @@ -52,12 +51,14 @@ button { display:inline-block;/*for ie*/ } input[type=submit], +input[type=button], input.submit { height:27px;/*for ff*/ line-height:1.5; } button, input[type=submit], +input[type=button], input.submit { padding:3px; background: #efefef; @@ -86,6 +87,7 @@ input.submit { margin-top:8px; } input[type=submit]:hover, +input[type=button]:hover, button:hover { cursor:pointer; background-color:#fff; @@ -149,6 +151,7 @@ p { .w100 { width: 100%; } .vh { visibility:hidden; } .vam { vertical-align:middle; } +.italic { font-style:italic; } .notification { padding:5px; background:#FDF; @@ -760,6 +763,7 @@ textarea:-moz-placeholder {/* for FF */ .article p { margin:0.8em 0; } +#md-edit-help ul, .article ul { list-style-type:disc; padding-left:2em; @@ -1746,13 +1750,16 @@ textarea:-moz-placeholder {/* for FF */ #docu-view, #svg-view, #pdf, -#md-view { +#md-view, +#md-edit { background:#fff; } -#md-view { +#md-view, +#md-edit { width:756px; 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+ + // Create the private state objects. + g_urls = new SaveHash(); + g_titles = new SaveHash(); + g_html_blocks = []; + g_list_level = 0; + + text = pluginHooks.preConversion(text); + + // attacklab: Replace ~ with ~T + // This lets us use tilde as an escape char to avoid md5 hashes + // The choice of character is arbitray; anything that isn't + // magic in Markdown will work. + text = text.replace(/~/g, "~T"); + + // attacklab: Replace $ with ~D + // RegExp interprets $ as a special character + // when it's in a replacement string + text = text.replace(/\$/g, "~D"); + + // Standardize line endings + text = text.replace(/\r\n/g, "\n"); // DOS to Unix + text = text.replace(/\r/g, "\n"); // Mac to Unix + + // Make sure text begins and ends with a couple of newlines: + text = "\n\n" + text + "\n\n"; + + // Convert all tabs to spaces. + text = _Detab(text); + + // Strip any lines consisting only of spaces and tabs. + // This makes subsequent regexen easier to write, because we can + // match consecutive blank lines with /\n+/ instead of something + // contorted like /[ \t]*\n+/ . + text = text.replace(/^[ \t]+$/mg, ""); + + text = pluginHooks.postNormalization(text); + + // Turn block-level HTML blocks into hash entries + text = _HashHTMLBlocks(text); + + // Strip link definitions, store in hashes. + text = _StripLinkDefinitions(text); + + text = _RunBlockGamut(text); + + text = _UnescapeSpecialChars(text); + + // attacklab: Restore dollar signs + text = text.replace(/~D/g, "$$"); + + // attacklab: Restore tildes + text = text.replace(/~T/g, "~"); + + text = pluginHooks.postConversion(text); + + g_html_blocks = g_titles = g_urls = null; + + return text; + }; + + function _StripLinkDefinitions(text) { + // + // Strips link definitions from text, stores the URLs and titles in + // hash references. + // + + // Link defs are in the form: ^[id]: url "optional title" + + /* + text = text.replace(/ + ^[ ]{0,3}\[(.+)\]: // id = $1 attacklab: g_tab_width - 1 + [ \t]* + \n? // maybe *one* newline + [ \t]* + ? // url = $2 + (?=\s|$) // lookahead for whitespace instead of the lookbehind removed below + [ \t]* + \n? // maybe one newline + [ \t]* + ( // (potential) title = $3 + (\n*) // any lines skipped = $4 attacklab: lookbehind removed + [ \t]+ + ["(] + (.+?) // title = $5 + [")] + [ \t]* + )? // title is optional + (?:\n+|$) + /gm, function(){...}); + */ + + text = text.replace(/^[ ]{0,3}\[(.+)\]:[ \t]*\n?[ \t]*?(?=\s|$)[ \t]*\n?[ \t]*((\n*)["(](.+?)[")][ \t]*)?(?:\n+)/gm, + function (wholeMatch, m1, m2, m3, m4, m5) { + m1 = m1.toLowerCase(); + g_urls.set(m1, _EncodeAmpsAndAngles(m2)); // Link IDs are case-insensitive + if (m4) { + // Oops, found blank lines, so it's not a title. + // Put back the parenthetical statement we stole. + return m3; + } else if (m5) { + g_titles.set(m1, m5.replace(/"/g, """)); + } + + // Completely remove the definition from the text + return ""; + } + ); + + return text; + } + + function _HashHTMLBlocks(text) { + + // Hashify HTML blocks: + // We only want to do this for block-level HTML tags, such as headers, + // lists, and tables. That's because we still want to wrap

s around + // "paragraphs" that are wrapped in non-block-level tags, such as anchors, + // phrase emphasis, and spans. The list of tags we're looking for is + // hard-coded: + var block_tags_a = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del" + var block_tags_b = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math" + + // First, look for nested blocks, e.g.: + //

+ //
+ // tags for inner block must be indented. + //
+ //
+ // + // The outermost tags must start at the left margin for this to match, and + // the inner nested divs must be indented. + // We need to do this before the next, more liberal match, because the next + // match will start at the first `
` and stop at the first `
`. + + // attacklab: This regex can be expensive when it fails. + + /* + text = text.replace(/ + ( // save in $1 + ^ // start of line (with /m) + <($block_tags_a) // start tag = $2 + \b // word break + // attacklab: hack around khtml/pcre bug... + [^\r]*?\n // any number of lines, minimally matching + // the matching end tag + [ \t]* // trailing spaces/tabs + (?=\n+) // followed by a newline + ) // attacklab: there are sentinel newlines at end of document + /gm,function(){...}}; + */ + text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del)\b[^\r]*?\n<\/\2>[ \t]*(?=\n+))/gm, hashElement); + + // + // Now match more liberally, simply from `\n` to `\n` + // + + /* + text = text.replace(/ + ( // save in $1 + ^ // start of line (with /m) + <($block_tags_b) // start tag = $2 + \b // word break + // attacklab: hack around khtml/pcre bug... + [^\r]*? // any number of lines, minimally matching + .* // the matching end tag + [ \t]* // trailing spaces/tabs + (?=\n+) // followed by a newline + ) // attacklab: there are sentinel newlines at end of document + /gm,function(){...}}; + */ + text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math)\b[^\r]*?.*<\/\2>[ \t]*(?=\n+)\n)/gm, hashElement); + + // Special case just for
. It was easier to make a special case than + // to make the other regex more complicated. + + /* + text = text.replace(/ + \n // Starting after a blank line + [ ]{0,3} + ( // save in $1 + (<(hr) // start tag = $2 + \b // word break + ([^<>])*? + \/?>) // the matching end tag + [ \t]* + (?=\n{2,}) // followed by a blank line + ) + /g,hashElement); + */ + text = text.replace(/\n[ ]{0,3}((<(hr)\b([^<>])*?\/?>)[ \t]*(?=\n{2,}))/g, hashElement); + + // Special case for standalone HTML comments: + + /* + text = text.replace(/ + \n\n // Starting after a blank line + [ ]{0,3} // attacklab: g_tab_width - 1 + ( // save in $1 + -]|-[^>])(?:[^-]|-[^-])*)--) // see http://www.w3.org/TR/html-markup/syntax.html#comments and http://meta.stackoverflow.com/q/95256 + > + [ \t]* + (?=\n{2,}) // followed by a blank line + ) + /g,hashElement); + */ + text = text.replace(/\n\n[ ]{0,3}(-]|-[^>])(?:[^-]|-[^-])*)--)>[ \t]*(?=\n{2,}))/g, hashElement); + + // PHP and ASP-style processor instructions ( and <%...%>) + + /* + text = text.replace(/ + (?: + \n\n // Starting after a blank line + ) + ( // save in $1 + [ ]{0,3} // attacklab: g_tab_width - 1 + (?: + <([?%]) // $2 + [^\r]*? + \2> + ) + [ \t]* + (?=\n{2,}) // followed by a blank line + ) + /g,hashElement); + */ + text = text.replace(/(?:\n\n)([ ]{0,3}(?:<([?%])[^\r]*?\2>)[ \t]*(?=\n{2,}))/g, hashElement); + + return text; + } + + function hashElement(wholeMatch, m1) { + var blockText = m1; + + // Undo double lines + blockText = blockText.replace(/^\n+/, ""); + + // strip trailing blank lines + blockText = blockText.replace(/\n+$/g, ""); + + // Replace the element text with a marker ("~KxK" where x is its key) + blockText = "\n\n~K" + (g_html_blocks.push(blockText) - 1) + "K\n\n"; + + return blockText; + } + + var blockGamutHookCallback = function (t) { return _RunBlockGamut(t); } + + function _RunBlockGamut(text, doNotUnhash) { + // + // These are all the transformations that form block-level + // tags like paragraphs, headers, and list items. + // + + text = pluginHooks.preBlockGamut(text, blockGamutHookCallback); + + text = _DoHeaders(text); + + // Do Horizontal Rules: + var replacement = "
\n"; + text = text.replace(/^[ ]{0,2}([ ]?\*[ ]?){3,}[ \t]*$/gm, replacement); + text = text.replace(/^[ ]{0,2}([ ]?-[ ]?){3,}[ \t]*$/gm, replacement); + text = text.replace(/^[ ]{0,2}([ ]?_[ ]?){3,}[ \t]*$/gm, replacement); + + text = _DoLists(text); + text = _DoCodeBlocks(text); + text = _DoBlockQuotes(text); + + text = pluginHooks.postBlockGamut(text, blockGamutHookCallback); + + // We already ran _HashHTMLBlocks() before, in Markdown(), but that + // was to escape raw HTML in the original Markdown source. This time, + // we're escaping the markup we've just created, so that we don't wrap + //

tags around block-level tags. + text = _HashHTMLBlocks(text); + text = _FormParagraphs(text, doNotUnhash); + + return text; + } + + function _RunSpanGamut(text) { + // + // These are all the transformations that occur *within* block-level + // tags like paragraphs, headers, and list items. + // + + text = pluginHooks.preSpanGamut(text); + + text = _DoCodeSpans(text); + text = _EscapeSpecialCharsWithinTagAttributes(text); + text = _EncodeBackslashEscapes(text); + + // Process anchor and image tags. Images must come first, + // because ![foo][f] looks like an anchor. + text = _DoImages(text); + text = _DoAnchors(text); + + // Make links out of things like `` + // Must come after _DoAnchors(), because you can use < and > + // delimiters in inline links like [this](). + text = _DoAutoLinks(text); + + text = text.replace(/~P/g, "://"); // put in place to prevent autolinking; reset now + + text = _EncodeAmpsAndAngles(text); + text = _DoItalicsAndBold(text); + + // Do hard breaks: + text = text.replace(/ +\n/g, "
\n"); + + text = pluginHooks.postSpanGamut(text); + + return text; + } + + function _EscapeSpecialCharsWithinTagAttributes(text) { + // + // Within tags -- meaning between < and > -- encode [\ ` * _] so they + // don't conflict with their use in Markdown for code, italics and strong. + // + + // Build a regex to find HTML tags and comments. See Friedl's + // "Mastering Regular Expressions", 2nd Ed., pp. 200-201. + + // SE: changed the comment part of the regex + + var regex = /(<[a-z\/!$]("[^"]*"|'[^']*'|[^'">])*>|-]|-[^>])(?:[^-]|-[^-])*)--)>)/gi; + + text = text.replace(regex, function (wholeMatch) { + var tag = wholeMatch.replace(/(.)<\/?code>(?=.)/g, "$1`"); + tag = escapeCharacters(tag, wholeMatch.charAt(1) == "!" ? "\\`*_/" : "\\`*_"); // also escape slashes in comments to prevent autolinking there -- http://meta.stackoverflow.com/questions/95987 + return tag; + }); + + return text; + } + + function _DoAnchors(text) { + // + // Turn Markdown link shortcuts into XHTML tags. + // + // + // First, handle reference-style links: [link text] [id] + // + + /* + text = text.replace(/ + ( // wrap whole match in $1 + \[ + ( + (?: + \[[^\]]*\] // allow brackets nested one level + | + [^\[] // or anything else + )* + ) + \] + + [ ]? // one optional space + (?:\n[ ]*)? // one optional newline followed by spaces + + \[ + (.*?) // id = $3 + \] + ) + ()()()() // pad remaining backreferences + /g, writeAnchorTag); + */ + text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g, writeAnchorTag); + + // + // Next, inline-style links: [link text](url "optional title") + // + + /* + text = text.replace(/ + ( // wrap whole match in $1 + \[ + ( + (?: + \[[^\]]*\] // allow brackets nested one level + | + [^\[\]] // or anything else + )* + ) + \] + \( // literal paren + [ \t]* + () // no id, so leave $3 empty + ? + [ \t]* + ( // $5 + (['"]) // quote char = $6 + (.*?) // Title = $7 + \6 // matching quote + [ \t]* // ignore any spaces/tabs between closing quote and ) + )? // title is optional + \) + ) + /g, writeAnchorTag); + */ + + text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\]\([ \t]*()?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g, writeAnchorTag); + + // + // Last, handle reference-style shortcuts: [link text] + // These must come last in case you've also got [link test][1] + // or [link test](/foo) + // + + /* + text = text.replace(/ + ( // wrap whole match in $1 + \[ + ([^\[\]]+) // link text = $2; can't contain '[' or ']' + \] + ) + ()()()()() // pad rest of backreferences + /g, writeAnchorTag); + */ + text = text.replace(/(\[([^\[\]]+)\])()()()()()/g, writeAnchorTag); + + return text; + } + + function writeAnchorTag(wholeMatch, m1, m2, m3, m4, m5, m6, m7) { + if (m7 == undefined) m7 = ""; + var whole_match = m1; + var link_text = m2.replace(/:\/\//g, "~P"); // to prevent auto-linking withing the link. will be converted back after the auto-linker runs + var link_id = m3.toLowerCase(); + var url = m4; + var title = m7; + + if (url == "") { + if (link_id == "") { + // lower-case and turn embedded newlines into spaces + link_id = link_text.toLowerCase().replace(/ ?\n/g, " "); + } + url = "#" + link_id; + + if (g_urls.get(link_id) != undefined) { + url = g_urls.get(link_id); + if (g_titles.get(link_id) != undefined) { + title = g_titles.get(link_id); + } + } + else { + if (whole_match.search(/\(\s*\)$/m) > -1) { + // Special case for explicit empty url + url = ""; + } else { + return whole_match; + } + } + } + url = encodeProblemUrlChars(url); + url = escapeCharacters(url, "*_"); + var result = ""; + + return result; + } + + function _DoImages(text) { + // + // Turn Markdown image shortcuts into tags. + // + + // + // First, handle reference-style labeled images: ![alt text][id] + // + + /* + text = text.replace(/ + ( // wrap whole match in $1 + !\[ + (.*?) // alt text = $2 + \] + + [ ]? // one optional space + (?:\n[ ]*)? // one optional newline followed by spaces + + \[ + (.*?) // id = $3 + \] + ) + ()()()() // pad rest of backreferences + /g, writeImageTag); + */ + text = text.replace(/(!\[(.*?)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g, writeImageTag); + + // + // Next, handle inline images: ![alt text](url "optional title") + // Don't forget: encode * and _ + + /* + text = text.replace(/ + ( // wrap whole match in $1 + !\[ + (.*?) // alt text = $2 + \] + \s? // One optional whitespace character + \( // literal paren + [ \t]* + () // no id, so leave $3 empty + ? // src url = $4 + [ \t]* + ( // $5 + (['"]) // quote char = $6 + (.*?) // title = $7 + \6 // matching quote + [ \t]* + )? // title is optional + \) + ) + /g, writeImageTag); + */ + text = text.replace(/(!\[(.*?)\]\s?\([ \t]*()?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g, writeImageTag); + + return text; + } + + function attributeEncode(text) { + // unconditionally replace angle brackets here -- what ends up in an attribute (e.g. alt or title) + // never makes sense to have verbatim HTML in it (and the sanitizer would totally break it) + return text.replace(/>/g, ">").replace(/" + _RunSpanGamut(m1) + "\n\n"; } + ); + + text = text.replace(/^(.+)[ \t]*\n-+[ \t]*\n+/gm, + function (matchFound, m1) { return "

" + _RunSpanGamut(m1) + "

\n\n"; } + ); + + // atx-style headers: + // # Header 1 + // ## Header 2 + // ## Header 2 with closing hashes ## + // ... + // ###### Header 6 + // + + /* + text = text.replace(/ + ^(\#{1,6}) // $1 = string of #'s + [ \t]* + (.+?) // $2 = Header text + [ \t]* + \#* // optional closing #'s (not counted) + \n+ + /gm, function() {...}); + */ + + text = text.replace(/^(\#{1,6})[ \t]*(.+?)[ \t]*\#*\n+/gm, + function (wholeMatch, m1, m2) { + var h_level = m1.length; + return "" + _RunSpanGamut(m2) + "\n\n"; + } + ); + + return text; + } + + function _DoLists(text) { + // + // Form HTML ordered (numbered) and unordered (bulleted) lists. + // + + // attacklab: add sentinel to hack around khtml/safari bug: + // http://bugs.webkit.org/show_bug.cgi?id=11231 + text += "~0"; + + // Re-usable pattern to match any entirel ul or ol list: + + /* + var whole_list = / + ( // $1 = whole list + ( // $2 + [ ]{0,3} // attacklab: g_tab_width - 1 + ([*+-]|\d+[.]) // $3 = first list item marker + [ \t]+ + ) + [^\r]+? + ( // $4 + ~0 // sentinel for workaround; should be $ + | + \n{2,} + (?=\S) + (?! // Negative lookahead for another list item marker + [ \t]* + (?:[*+-]|\d+[.])[ \t]+ + ) + ) + ) + /g + */ + var whole_list = /^(([ ]{0,3}([*+-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+-]|\d+[.])[ \t]+)))/gm; + + if (g_list_level) { + text = text.replace(whole_list, function (wholeMatch, m1, m2) { + var list = m1; + var list_type = (m2.search(/[*+-]/g) > -1) ? "ul" : "ol"; + + var result = _ProcessListItems(list, list_type); + + // Trim any trailing whitespace, to put the closing `` + // up on the preceding line, to get it past the current stupid + // HTML block parser. This is a hack to work around the terrible + // hack that is the HTML block parser. + result = result.replace(/\s+$/, ""); + result = "<" + list_type + ">" + result + "\n"; + return result; + }); + } else { + whole_list = /(\n\n|^\n?)(([ ]{0,3}([*+-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+-]|\d+[.])[ \t]+)))/g; + text = text.replace(whole_list, function (wholeMatch, m1, m2, m3) { + var runup = m1; + var list = m2; + + var list_type = (m3.search(/[*+-]/g) > -1) ? "ul" : "ol"; + var result = _ProcessListItems(list, list_type); + result = runup + "<" + list_type + ">\n" + result + "\n"; + return result; + }); + } + + // attacklab: strip sentinel + text = text.replace(/~0/, ""); + + return text; + } + + var _listItemMarkers = { ol: "\\d+[.]", ul: "[*+-]" }; + + function _ProcessListItems(list_str, list_type) { + // + // Process the contents of a single ordered or unordered list, splitting it + // into individual list items. + // + // list_type is either "ul" or "ol". + + // The $g_list_level global keeps track of when we're inside a list. + // Each time we enter a list, we increment it; when we leave a list, + // we decrement. If it's zero, we're not in a list anymore. + // + // We do this because when we're not inside a list, we want to treat + // something like this: + // + // I recommend upgrading to version + // 8. Oops, now this line is treated + // as a sub-list. + // + // As a single paragraph, despite the fact that the second line starts + // with a digit-period-space sequence. + // + // Whereas when we're inside a list (or sub-list), that line will be + // treated as the start of a sub-list. What a kludge, huh? This is + // an aspect of Markdown's syntax that's hard to parse perfectly + // without resorting to mind-reading. Perhaps the solution is to + // change the syntax rules such that sub-lists must start with a + // starting cardinal number; e.g. "1." or "a.". + + g_list_level++; + + // trim trailing blank lines: + list_str = list_str.replace(/\n{2,}$/, "\n"); + + // attacklab: add sentinel to emulate \z + list_str += "~0"; + + // In the original attacklab showdown, list_type was not given to this function, and anything + // that matched /[*+-]|\d+[.]/ would just create the next
  • , causing this mismatch: + // + // Markdown rendered by WMD rendered by MarkdownSharp + // ------------------------------------------------------------------ + // 1. first 1. first 1. first + // 2. second 2. second 2. second + // - third 3. third * third + // + // We changed this to behave identical to MarkdownSharp. This is the constructed RegEx, + // with {MARKER} being one of \d+[.] or [*+-], depending on list_type: + + /* + list_str = list_str.replace(/ + (^[ \t]*) // leading whitespace = $1 + ({MARKER}) [ \t]+ // list marker = $2 + ([^\r]+? // list item text = $3 + (\n+) + ) + (?= + (~0 | \2 ({MARKER}) [ \t]+) + ) + /gm, function(){...}); + */ + + var marker = _listItemMarkers[list_type]; + var re = new RegExp("(^[ \\t]*)(" + marker + ")[ \\t]+([^\\r]+?(\\n+))(?=(~0|\\1(" + marker + ")[ \\t]+))", "gm"); + var last_item_had_a_double_newline = false; + list_str = list_str.replace(re, + function (wholeMatch, m1, m2, m3) { + var item = m3; + var leading_space = m1; + var ends_with_double_newline = /\n\n$/.test(item); + var contains_double_newline = ends_with_double_newline || item.search(/\n{2,}/) > -1; + + if (contains_double_newline || last_item_had_a_double_newline) { + item = _RunBlockGamut(_Outdent(item), /* doNotUnhash = */true); + } + else { + // Recursion for sub-lists: + item = _DoLists(_Outdent(item)); + item = item.replace(/\n$/, ""); // chomp(item) + item = _RunSpanGamut(item); + } + last_item_had_a_double_newline = ends_with_double_newline; + return "
  • " + item + "
    • \n"; + } + ); + + // attacklab: strip sentinel + list_str = list_str.replace(/~0/g, ""); + + g_list_level--; + return list_str; + } + + function _DoCodeBlocks(text) { + // + // Process Markdown `
    ` blocks.
+            //  
+
+            /*
+            text = text.replace(/
+                (?:\n\n|^)
+                (                               // $1 = the code block -- one or more lines, starting with a space/tab
+                    (?:
+                        (?:[ ]{4}|\t)           // Lines must start with a tab or a tab-width of spaces - attacklab: g_tab_width
+                        .*\n+
+                    )+
+                )
+                (\n*[ ]{0,3}[^ \t\n]|(?=~0))    // attacklab: g_tab_width
+            /g ,function(){...});
+            */
+
+            // attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
+            text += "~0";
+
+            text = text.replace(/(?:\n\n|^\n?)((?:(?:[ ]{4}|\t).*\n+)+)(\n*[ ]{0,3}[^ \t\n]|(?=~0))/g,
+                function (wholeMatch, m1, m2) {
+                    var codeblock = m1;
+                    var nextChar = m2;
+
+                    codeblock = _EncodeCode(_Outdent(codeblock));
+                    codeblock = _Detab(codeblock);
+                    codeblock = codeblock.replace(/^\n+/g, ""); // trim leading newlines
+                    codeblock = codeblock.replace(/\n+$/g, ""); // trim trailing whitespace
+
+                    codeblock = "
    " + codeblock + "\n
    ";
+
+                    return "\n\n" + codeblock + "\n\n" + nextChar;
+                }
+            );
+
+            // attacklab: strip sentinel
+            text = text.replace(/~0/, "");
+
+            return text;
+        }
+
+        function hashBlock(text) {
+            text = text.replace(/(^\n+|\n+$)/g, "");
+            return "\n\n~K" + (g_html_blocks.push(text) - 1) + "K\n\n";
+        }
+
+        function _DoCodeSpans(text) {
+            //
+            // * Backtick quotes are used for  spans.
+            // 
+            // * You can use multiple backticks as the delimiters if you want to
+            //   include literal backticks in the code span. So, this input:
+            //     
+            //      Just type ``foo `bar` baz`` at the prompt.
+            //     
+            //   Will translate to:
+            //     
+            //      
    Just type foo `bar` baz at the prompt.
    
+            //     
+            //   There's no arbitrary limit to the number of backticks you
+            //   can use as delimters. If you need three consecutive backticks
+            //   in your code, use four for delimiters, etc.
+            //
+            // * You can use spaces to get literal backticks at the edges:
+            //     
+            //      ... type `` `bar` `` ...
+            //     
+            //   Turns to:
+            //     
+            //      ... type `bar` ...
+            //
+
+            /*
+            text = text.replace(/
+                (^|[^\\])       // Character before opening ` can't be a backslash
+                (`+)            // $2 = Opening run of `
+                (               // $3 = The code block
+                    [^\r]*?
+                    [^`]        // attacklab: work around lack of lookbehind
+                )
+                \2              // Matching closer
+                (?!`)
+            /gm, function(){...});
+            */
+
+            text = text.replace(/(^|[^\\])(`+)([^\r]*?[^`])\2(?!`)/gm,
+                function (wholeMatch, m1, m2, m3, m4) {
+                    var c = m3;
+                    c = c.replace(/^([ \t]*)/g, ""); // leading whitespace
+                    c = c.replace(/[ \t]*$/g, ""); // trailing whitespace
+                    c = _EncodeCode(c);
+                    c = c.replace(/:\/\//g, "~P"); // to prevent auto-linking. Not necessary in code *blocks*, but in code spans. Will be converted back after the auto-linker runs.
+                    return m1 + "" + c + "";
+                }
+            );
+
+            return text;
+        }
+
+        function _EncodeCode(text) {
+            //
+            // Encode/escape certain characters inside Markdown code runs.
+            // The point is that in code, these characters are literals,
+            // and lose their special Markdown meanings.
+            //
+            // Encode all ampersands; HTML entities are not
+            // entities within a Markdown code span.
+            text = text.replace(/&/g, "&");
+
+            // Do the angle bracket song and dance:
+            text = text.replace(//g, ">");
+
+            // Now, escape characters that are magic in Markdown:
+            text = escapeCharacters(text, "\*_{}[]\\", false);
+
+            // jj the line above breaks this:
+            //---
+
+            //* Item
+
+            //   1. Subitem
+
+            //            special char: *
+            //---
+
+            return text;
+        }
+
+        function _DoItalicsAndBold(text) {
+
+            //  must go first:
+            text = text.replace(/([\W_]|^)(\*\*|__)(?=\S)([^\r]*?\S[\*_]*)\2([\W_]|$)/g,
+            "$1$3$4");
+
+            text = text.replace(/([\W_]|^)(\*|_)(?=\S)([^\r\*_]*?\S)\2([\W_]|$)/g,
+            "$1$3$4");
+
+            return text;
+        }
+
+        function _DoBlockQuotes(text) {
+
+            /*
+            text = text.replace(/
+                (                           // Wrap whole match in $1
+                    (
+                        ^[ \t]*>[ \t]?      // '>' at the start of a line
+                        .+\n                // rest of the first line
+                        (.+\n)*             // subsequent consecutive lines
+                        \n*                 // blanks
+                    )+
+                )
+            /gm, function(){...});
+            */
+
+            text = text.replace(/((^[ \t]*>[ \t]?.+\n(.+\n)*\n*)+)/gm,
+                function (wholeMatch, m1) {
+                    var bq = m1;
+
+                    // attacklab: hack around Konqueror 3.5.4 bug:
+                    // "----------bug".replace(/^-/g,"") == "bug"
+
+                    bq = bq.replace(/^[ \t]*>[ \t]?/gm, "~0"); // trim one level of quoting
+
+                    // attacklab: clean up hack
+                    bq = bq.replace(/~0/g, "");
+
+                    bq = bq.replace(/^[ \t]+$/gm, "");     // trim whitespace-only lines
+                    bq = _RunBlockGamut(bq);             // recurse
+
+                    bq = bq.replace(/(^|\n)/g, "$1  ");
+                    // These leading spaces screw with 
     content, so we need to fix that:
+                    bq = bq.replace(
+                            /(\s*
    [^\r]+?<\/pre>)/gm,
+                        function (wholeMatch, m1) {
+                            var pre = m1;
+                            // attacklab: hack around Konqueror 3.5.4 bug:
+                            pre = pre.replace(/^  /mg, "~0");
+                            pre = pre.replace(/~0/g, "");
+                            return pre;
+                        });
+
+                    return hashBlock("
    \n" + bq + "\n
    ");
+                }
+            );
+            return text;
+        }
+
+        function _FormParagraphs(text, doNotUnhash) {
+            //
+            //  Params:
+            //    $text - string to process with html 
     tags
+            //
+
+            // Strip leading and trailing lines:
+            text = text.replace(/^\n+/g, "");
+            text = text.replace(/\n+$/g, "");
+
+            var grafs = text.split(/\n{2,}/g);
+            var grafsOut = [];
+            
+            var markerRe = /~K(\d+)K/;
+
+            //
+            // Wrap 
     tags.
+            //
+            var end = grafs.length;
+            for (var i = 0; i < end; i++) {
+                var str = grafs[i];
+
+                // if this is an HTML marker, copy it
+                if (markerRe.test(str)) {
+                    grafsOut.push(str);
+                }
+                else if (/\S/.test(str)) {
+                    str = _RunSpanGamut(str);
+                    str = str.replace(/^([ \t]*)/g, "
    ");
+                    str += "
    "
+                    grafsOut.push(str);
+                }
+
+            }
+            //
+            // Unhashify HTML blocks
+            //
+            if (!doNotUnhash) {
+                end = grafsOut.length;
+                for (var i = 0; i < end; i++) {
+                    var foundAny = true;
+                    while (foundAny) { // we may need several runs, since the data may be nested
+                        foundAny = false;
+                        grafsOut[i] = grafsOut[i].replace(/~K(\d+)K/g, function (wholeMatch, id) {
+                            foundAny = true;
+                            return g_html_blocks[id];
+                        });
+                    }
+                }
+            }
+            return grafsOut.join("\n\n");
+        }
+
+        function _EncodeAmpsAndAngles(text) {
+            // Smart processing for ampersands and angle brackets that need to be encoded.
+
+            // Ampersand-encoding based entirely on Nat Irons's Amputator MT plugin:
+            //   http://bumppo.net/projects/amputator/
+            text = text.replace(/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/g, "&");
+
+            // Encode naked <'s
+            text = text.replace(/<(?![a-z\/?!]|~D)/gi, "<");
+
+            return text;
+        }
+
+        function _EncodeBackslashEscapes(text) {
+            //
+            //   Parameter:  String.
+            //   Returns:    The string, with after processing the following backslash
+            //               escape sequences.
+            //
+
+            // attacklab: The polite way to do this is with the new
+            // escapeCharacters() function:
+            //
+            //     text = escapeCharacters(text,"\\",true);
+            //     text = escapeCharacters(text,"`*_{}[]()>#+-.!",true);
+            //
+            // ...but we're sidestepping its use of the (slow) RegExp constructor
+            // as an optimization for Firefox.  This function gets called a LOT.
+
+            text = text.replace(/\\(\\)/g, escapeCharacters_callback);
+            text = text.replace(/\\([`*_{}\[\]()>#+-.!])/g, escapeCharacters_callback);
+            return text;
+        }
+        
+        function handleTrailingParens(wholeMatch, lookbehind, protocol, link) {
+            if (lookbehind)
+                return wholeMatch;
+            if (link.charAt(link.length - 1) !== ")")
+                return "<" + protocol + link + ">";
+            var parens = link.match(/[()]/g);
+            var level = 0;
+            for (var i = 0; i < parens.length; i++) {
+                if (parens[i] === "(") {
+                    if (level <= 0)
+                        level = 1;
+                    else
+                        level++;
+                }
+                else {
+                    level--;
+                }
+            }
+            var tail = "";
+            if (level < 0) {
+                var re = new RegExp("\\){1," + (-level) + "}$");
+                link = link.replace(re, function (trailingParens) {
+                    tail = trailingParens;
+                    return "";
+                });
+            }
+            
+            return "<" + protocol + link + ">" + tail;
+        }
+
+        function _DoAutoLinks(text) {
+
+            // note that at this point, all other URL in the text are already hyperlinked as     
+            // *except* for the  case
+
+            // automatically add < and > around unadorned raw hyperlinks
+            // must be preceded by a non-word character (and not by =" or <) and followed by non-word/EOF character
+            // simulating the lookbehind in a consuming way is okay here, since a URL can neither and with a " nor
+            // with a <, so there is no risk of overlapping matches.
+            text = text.replace(/(="|<)?\b(https?|ftp)(:\/\/[-A-Z0-9+&@#\/%?=~_|\[\]\(\)!:,\.;]*[-A-Z0-9+&@#\/%=~_|\[\])])(?=$|\W)/gi, handleTrailingParens);
+
+            //  autolink anything like 
+            
+            var replacer = function (wholematch, m1) { return "" + pluginHooks.plainLinkText(m1) + ""; }
+            text = text.replace(/<((https?|ftp):[^'">\s]+)>/gi, replacer);
+
+            // Email addresses: 
+            /*
+            text = text.replace(/
+                <
+                (?:mailto:)?
+                (
+                    [-.\w]+
+                    \@
+                    [-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
+                )
+                >
+            /gi, _DoAutoLinks_callback());
+            */
+
+            /* disabling email autolinking, since we don't do that on the server, either
+            text = text.replace(/<(?:mailto:)?([-.\w]+\@[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+)>/gi,
+                function(wholeMatch,m1) {
+                    return _EncodeEmailAddress( _UnescapeSpecialChars(m1) );
+                }
+            );
+            */
+            return text;
+        }
+
+        function _UnescapeSpecialChars(text) {
+            //
+            // Swap back in all the special characters we've hidden.
+            //
+            text = text.replace(/~E(\d+)E/g,
+                function (wholeMatch, m1) {
+                    var charCodeToReplace = parseInt(m1);
+                    return String.fromCharCode(charCodeToReplace);
+                }
+            );
+            return text;
+        }
+
+        function _Outdent(text) {
+            //
+            // Remove one level of line-leading tabs or spaces
+            //
+
+            // attacklab: hack around Konqueror 3.5.4 bug:
+            // "----------bug".replace(/^-/g,"") == "bug"
+
+            text = text.replace(/^(\t|[ ]{1,4})/gm, "~0"); // attacklab: g_tab_width
+
+            // attacklab: clean up hack
+            text = text.replace(/~0/g, "")
+
+            return text;
+        }
+
+        function _Detab(text) {
+            if (!/\t/.test(text))
+                return text;
+
+            var spaces = ["    ", "   ", "  ", " "],
+            skew = 0,
+            v;
+
+            return text.replace(/[\n\t]/g, function (match, offset) {
+                if (match === "\n") {
+                    skew = offset + 1;
+                    return match;
+                }
+                v = (offset - skew) % 4;
+                skew = offset + 1;
+                return spaces[v];
+            });
+        }
+
+        //
+        //  attacklab: Utility functions
+        //
+
+        var _problemUrlChars = /(?:["'*()[\]:]|~D)/g;
+
+        // hex-encodes some unusual "problem" chars in URLs to avoid URL detection problems 
+        function encodeProblemUrlChars(url) {
+            if (!url)
+                return "";
+
+            var len = url.length;
+
+            return url.replace(_problemUrlChars, function (match, offset) {
+                if (match == "~D") // escape for dollar
+                    return "%24";
+                if (match == ":") {
+                    if (offset == len - 1 || /[0-9\/]/.test(url.charAt(offset + 1)))
+                        return ":"
+                }
+                return "%" + match.charCodeAt(0).toString(16);
+            });
+        }
+
+
+        function escapeCharacters(text, charsToEscape, afterBackslash) {
+            // First we have to escape the escape characters so that
+            // we can build a character class out of them
+            var regexString = "([" + charsToEscape.replace(/([\[\]\\])/g, "\\$1") + "])";
+
+            if (afterBackslash) {
+                regexString = "\\\\" + regexString;
+            }
+
+            var regex = new RegExp(regexString, "g");
+            text = text.replace(regex, escapeCharacters_callback);
+
+            return text;
+        }
+
+
+        function escapeCharacters_callback(wholeMatch, m1) {
+            var charCodeToEscape = m1.charCodeAt(0);
+            return "~E" + charCodeToEscape + "E";
+        }
+
+    }; // end of the Markdown.Converter constructor
+
+})();
diff --git a/media/js/Markdown.Editor.js b/media/js/Markdown.Editor.js
new file mode 100644
index 0000000000..703d5e4ee2
--- /dev/null
+++ b/media/js/Markdown.Editor.js
@@ -0,0 +1,2203 @@
+// needs Markdown.Converter.js at the moment
+
+(function () {
+
+    var util = {},
+        position = {},
+        ui = {},
+        doc = window.document,
+        re = window.RegExp,
+        nav = window.navigator,
+        SETTINGS = { lineLength: 72 },
+
+    // Used to work around some browser bugs where we can't use feature testing.
+        uaSniffed = {
+            isIE: /msie/.test(nav.userAgent.toLowerCase()),
+            isIE_5or6: /msie 6/.test(nav.userAgent.toLowerCase()) || /msie 5/.test(nav.userAgent.toLowerCase()),
+            isOpera: /opera/.test(nav.userAgent.toLowerCase())
+        };
+
+    var defaultsStrings = {
+        bold: "Strong  Ctrl+B",
+        boldexample: "strong text",
+
+        italic: "Emphasis  Ctrl+I",
+        italicexample: "emphasized text",
+
+        link: "Hyperlink  Ctrl+L",
+        linkdescription: "enter link description here",
+        linkdialog: "
    Insert Hyperlink
    http://example.com/ \"optional title\"
    ",
+
+        quote: "Blockquote 
     Ctrl+Q",
+        quoteexample: "Blockquote",
+
+        code: "Code Sample 
     Ctrl+K",
+        codeexample: "enter code here",
+
+        image: "Image  Ctrl+G",
+        imagedescription: "enter image description here",
+        imagedialog: "
    Insert Image
    http://example.com/images/diagram.jpg \"optional title\"
    ",
+
+        olist: "Numbered List 
       Ctrl+O",
+        ulist: "Bulleted List 
         Ctrl+U",
+        litem: "List item",
+
+        heading: "Heading 
        /
         Ctrl+H",
+        headingexample: "Heading",
+
+        hr: "Horizontal Rule 
         Ctrl+R",
+
+        undo: "Undo - Ctrl+Z",
+        redo: "Redo - Ctrl+Y",
+        redomac: "Redo - Ctrl+Shift+Z",
+
+        help: "Markdown Editing Help"
+    };
+
+
+    // -------------------------------------------------------------------
+    //  YOUR CHANGES GO HERE
+    //
+    // I've tried to localize the things you are likely to change to
+    // this area.
+    // -------------------------------------------------------------------
+
+    // The default text that appears in the dialog input box when entering
+    // links.
+    var imageDefaultText = "http://";
+    var linkDefaultText = "http://";
+
+    // -------------------------------------------------------------------
+    //  END OF YOUR CHANGES
+    // -------------------------------------------------------------------
+
+    // options, if given, can have the following properties:
+    //   options.helpButton = { handler: yourEventHandler }
+    //   options.strings = { italicexample: "slanted text" }
+    // `yourEventHandler` is the click handler for the help button.
+    // If `options.helpButton` isn't given, not help button is created.
+    // `options.strings` can have any or all of the same properties as
+    // `defaultStrings` above, so you can just override some string displayed
+    // to the user on a case-by-case basis, or translate all strings to
+    // a different language.
+    //
+    // For backwards compatibility reasons, the `options` argument can also
+    // be just the `helpButton` object, and `strings.help` can also be set via
+    // `helpButton.title`. This should be considered legacy.
+    //
+    // The constructed editor object has the methods:
+    // - getConverter() returns the markdown converter object that was passed to the constructor
+    // - run() actually starts the editor; should be called after all necessary plugins are registered. Calling this more than once is a no-op.
+    // - refreshPreview() forces the preview to be updated. This method is only available after run() was called.
+    Markdown.Editor = function (markdownConverter, idPostfix, options) {
+        
+        options = options || {};
+
+        if (typeof options.handler === "function") { //backwards compatible behavior
+            options = { helpButton: options };
+        }
+        options.strings = options.strings || {};
+        if (options.helpButton) {
+            options.strings.help = options.strings.help || options.helpButton.title;
+        }
+        var getString = function (identifier) { return options.strings[identifier] || defaultsStrings[identifier]; }
+
+        idPostfix = idPostfix || "";
+
+        var hooks = this.hooks = new Markdown.HookCollection();
+        hooks.addNoop("onPreviewRefresh");       // called with no arguments after the preview has been refreshed
+        hooks.addNoop("postBlockquoteCreation"); // called with the user's selection *after* the blockquote was created; should return the actual to-be-inserted text
+        hooks.addFalse("insertImageDialog");     /* called with one parameter: a callback to be called with the URL of the image. If the application creates
+                                                  * its own image insertion dialog, this hook should return true, and the callback should be called with the chosen
+                                                  * image url (or null if the user cancelled). If this hook returns false, the default dialog will be used.
+                                                  */
+
+        this.getConverter = function () { return markdownConverter; }
+
+        var that = this,
+            panels;
+
+        this.run = function () {
+            if (panels)
+                return; // already initialized
+
+            panels = new PanelCollection(idPostfix);
+            var commandManager = new CommandManager(hooks, getString);
+            var previewManager = new PreviewManager(markdownConverter, panels, function () { hooks.onPreviewRefresh(); });
+            var undoManager, uiManager;
+
+            if (!/\?noundo/.test(doc.location.href)) {
+                undoManager = new UndoManager(function () {
+                    previewManager.refresh();
+                    if (uiManager) // not available on the first call
+                        uiManager.setUndoRedoButtonStates();
+                }, panels);
+                this.textOperation = function (f) {
+                    undoManager.setCommandMode();
+                    f();
+                    that.refreshPreview();
+                }
+            }
+
+            uiManager = new UIManager(idPostfix, panels, undoManager, previewManager, commandManager, options.helpButton, getString);
+            uiManager.setUndoRedoButtonStates();
+
+            var forceRefresh = that.refreshPreview = function () { previewManager.refresh(true); };
+
+            forceRefresh();
+        };
+
+    }
+
+    // before: contains all the text in the input box BEFORE the selection.
+    // after: contains all the text in the input box AFTER the selection.
+    function Chunks() { }
+
+    // startRegex: a regular expression to find the start tag
+    // endRegex: a regular expresssion to find the end tag
+    Chunks.prototype.findTags = function (startRegex, endRegex) {
+
+        var chunkObj = this;
+        var regex;
+
+        if (startRegex) {
+
+            regex = util.extendRegExp(startRegex, "", "$");
+
+            this.before = this.before.replace(regex,
+                function (match) {
+                    chunkObj.startTag = chunkObj.startTag + match;
+                    return "";
+                });
+
+            regex = util.extendRegExp(startRegex, "^", "");
+
+            this.selection = this.selection.replace(regex,
+                function (match) {
+                    chunkObj.startTag = chunkObj.startTag + match;
+                    return "";
+                });
+        }
+
+        if (endRegex) {
+
+            regex = util.extendRegExp(endRegex, "", "$");
+
+            this.selection = this.selection.replace(regex,
+                function (match) {
+                    chunkObj.endTag = match + chunkObj.endTag;
+                    return "";
+                });
+
+            regex = util.extendRegExp(endRegex, "^", "");
+
+            this.after = this.after.replace(regex,
+                function (match) {
+                    chunkObj.endTag = match + chunkObj.endTag;
+                    return "";
+                });
+        }
+    };
+
+    // If remove is false, the whitespace is transferred
+    // to the before/after regions.
+    //
+    // If remove is true, the whitespace disappears.
+    Chunks.prototype.trimWhitespace = function (remove) {
+        var beforeReplacer, afterReplacer, that = this;
+        if (remove) {
+            beforeReplacer = afterReplacer = "";
+        } else {
+            beforeReplacer = function (s) { that.before += s; return ""; }
+            afterReplacer = function (s) { that.after = s + that.after; return ""; }
+        }
+
+        this.selection = this.selection.replace(/^(\s*)/, beforeReplacer).replace(/(\s*)$/, afterReplacer);
+    };
+
+
+    Chunks.prototype.skipLines = function (nLinesBefore, nLinesAfter, findExtraNewlines) {
+
+        if (nLinesBefore === undefined) {
+            nLinesBefore = 1;
+        }
+
+        if (nLinesAfter === undefined) {
+            nLinesAfter = 1;
+        }
+
+        nLinesBefore++;
+        nLinesAfter++;
+
+        var regexText;
+        var replacementText;
+
+        // chrome bug ... documented at: http://meta.stackoverflow.com/questions/63307/blockquote-glitch-in-editor-in-chrome-6-and-7/65985#65985
+        if (navigator.userAgent.match(/Chrome/)) {
+            "X".match(/()./);
+        }
+
+        this.selection = this.selection.replace(/(^\n*)/, "");
+
+        this.startTag = this.startTag + re.$1;
+
+        this.selection = this.selection.replace(/(\n*$)/, "");
+        this.endTag = this.endTag + re.$1;
+        this.startTag = this.startTag.replace(/(^\n*)/, "");
+        this.before = this.before + re.$1;
+        this.endTag = this.endTag.replace(/(\n*$)/, "");
+        this.after = this.after + re.$1;
+
+        if (this.before) {
+
+            regexText = replacementText = "";
+
+            while (nLinesBefore--) {
+                regexText += "\\n?";
+                replacementText += "\n";
+            }
+
+            if (findExtraNewlines) {
+                regexText = "\\n*";
+            }
+            this.before = this.before.replace(new re(regexText + "$", ""), replacementText);
+        }
+
+        if (this.after) {
+
+            regexText = replacementText = "";
+
+            while (nLinesAfter--) {
+                regexText += "\\n?";
+                replacementText += "\n";
+            }
+            if (findExtraNewlines) {
+                regexText = "\\n*";
+            }
+
+            this.after = this.after.replace(new re(regexText, ""), replacementText);
+        }
+    };
+
+    // end of Chunks
+
+    // A collection of the important regions on the page.
+    // Cached so we don't have to keep traversing the DOM.
+    // Also holds ieCachedRange and ieCachedScrollTop, where necessary; working around
+    // this issue:
+    // Internet explorer has problems with CSS sprite buttons that use HTML
+    // lists.  When you click on the background image "button", IE will
+    // select the non-existent link text and discard the selection in the
+    // textarea.  The solution to this is to cache the textarea selection
+    // on the button's mousedown event and set a flag.  In the part of the
+    // code where we need to grab the selection, we check for the flag
+    // and, if it's set, use the cached area instead of querying the
+    // textarea.
+    //
+    // This ONLY affects Internet Explorer (tested on versions 6, 7
+    // and 8) and ONLY on button clicks.  Keyboard shortcuts work
+    // normally since the focus never leaves the textarea.
+    function PanelCollection(postfix) {
+        this.buttonBar = doc.getElementById("wmd-button-bar" + postfix);
+        this.preview = doc.getElementById("wmd-preview" + postfix);
+        this.input = doc.getElementById("wmd-input" + postfix);
+    };
+
+    // Returns true if the DOM element is visible, false if it's hidden.
+    // Checks if display is anything other than none.
+    util.isVisible = function (elem) {
+
+        if (window.getComputedStyle) {
+            // Most browsers
+            return window.getComputedStyle(elem, null).getPropertyValue("display") !== "none";
+        }
+        else if (elem.currentStyle) {
+            // IE
+            return elem.currentStyle["display"] !== "none";
+        }
+    };
+
+
+    // Adds a listener callback to a DOM element which is fired on a specified
+    // event.
+    util.addEvent = function (elem, event, listener) {
+        if (elem.attachEvent) {
+            // IE only.  The "on" is mandatory.
+            elem.attachEvent("on" + event, listener);
+        }
+        else {
+            // Other browsers.
+            elem.addEventListener(event, listener, false);
+        }
+    };
+
+
+    // Removes a listener callback from a DOM element which is fired on a specified
+    // event.
+    util.removeEvent = function (elem, event, listener) {
+        if (elem.detachEvent) {
+            // IE only.  The "on" is mandatory.
+            elem.detachEvent("on" + event, listener);
+        }
+        else {
+            // Other browsers.
+            elem.removeEventListener(event, listener, false);
+        }
+    };
+
+    // Converts \r\n and \r to \n.
+    util.fixEolChars = function (text) {
+        text = text.replace(/\r\n/g, "\n");
+        text = text.replace(/\r/g, "\n");
+        return text;
+    };
+
+    // Extends a regular expression.  Returns a new RegExp
+    // using pre + regex + post as the expression.
+    // Used in a few functions where we have a base
+    // expression and we want to pre- or append some
+    // conditions to it (e.g. adding "$" to the end).
+    // The flags are unchanged.
+    //
+    // regex is a RegExp, pre and post are strings.
+    util.extendRegExp = function (regex, pre, post) {
+
+        if (pre === null || pre === undefined) {
+            pre = "";
+        }
+        if (post === null || post === undefined) {
+            post = "";
+        }
+
+        var pattern = regex.toString();
+        var flags;
+
+        // Replace the flags with empty space and store them.
+        pattern = pattern.replace(/\/([gim]*)$/, function (wholeMatch, flagsPart) {
+            flags = flagsPart;
+            return "";
+        });
+
+        // Remove the slash delimiters on the regular expression.
+        pattern = pattern.replace(/(^\/|\/$)/g, "");
+        pattern = pre + pattern + post;
+
+        return new re(pattern, flags);
+    }
+
+    // UNFINISHED
+    // The assignment in the while loop makes jslint cranky.
+    // I'll change it to a better loop later.
+    position.getTop = function (elem, isInner) {
+        var result = elem.offsetTop;
+        if (!isInner) {
+            while (elem = elem.offsetParent) {
+                result += elem.offsetTop;
+            }
+        }
+        return result;
+    };
+
+    position.getHeight = function (elem) {
+        return elem.offsetHeight || elem.scrollHeight;
+    };
+
+    position.getWidth = function (elem) {
+        return elem.offsetWidth || elem.scrollWidth;
+    };
+
+    position.getPageSize = function () {
+
+        var scrollWidth, scrollHeight;
+        var innerWidth, innerHeight;
+
+        // It's not very clear which blocks work with which browsers.
+        if (self.innerHeight && self.scrollMaxY) {
+            scrollWidth = doc.body.scrollWidth;
+            scrollHeight = self.innerHeight + self.scrollMaxY;
+        }
+        else if (doc.body.scrollHeight > doc.body.offsetHeight) {
+            scrollWidth = doc.body.scrollWidth;
+            scrollHeight = doc.body.scrollHeight;
+        }
+        else {
+            scrollWidth = doc.body.offsetWidth;
+            scrollHeight = doc.body.offsetHeight;
+        }
+
+        if (self.innerHeight) {
+            // Non-IE browser
+            innerWidth = self.innerWidth;
+            innerHeight = self.innerHeight;
+        }
+        else if (doc.documentElement && doc.documentElement.clientHeight) {
+            // Some versions of IE (IE 6 w/ a DOCTYPE declaration)
+            innerWidth = doc.documentElement.clientWidth;
+            innerHeight = doc.documentElement.clientHeight;
+        }
+        else if (doc.body) {
+            // Other versions of IE
+            innerWidth = doc.body.clientWidth;
+            innerHeight = doc.body.clientHeight;
+        }
+
+        var maxWidth = Math.max(scrollWidth, innerWidth);
+        var maxHeight = Math.max(scrollHeight, innerHeight);
+        return [maxWidth, maxHeight, innerWidth, innerHeight];
+    };
+
+    // Handles pushing and popping TextareaStates for undo/redo commands.
+    // I should rename the stack variables to list.
+    function UndoManager(callback, panels) {
+
+        var undoObj = this;
+        var undoStack = []; // A stack of undo states
+        var stackPtr = 0; // The index of the current state
+        var mode = "none";
+        var lastState; // The last state
+        var timer; // The setTimeout handle for cancelling the timer
+        var inputStateObj;
+
+        // Set the mode for later logic steps.
+        var setMode = function (newMode, noSave) {
+            if (mode != newMode) {
+                mode = newMode;
+                if (!noSave) {
+                    saveState();
+                }
+            }
+
+            if (!uaSniffed.isIE || mode != "moving") {
+                timer = setTimeout(refreshState, 1);
+            }
+            else {
+                inputStateObj = null;
+            }
+        };
+
+        var refreshState = function (isInitialState) {
+            inputStateObj = new TextareaState(panels, isInitialState);
+            timer = undefined;
+        };
+
+        this.setCommandMode = function () {
+            mode = "command";
+            saveState();
+            timer = setTimeout(refreshState, 0);
+        };
+
+        this.canUndo = function () {
+            return stackPtr > 1;
+        };
+
+        this.canRedo = function () {
+            if (undoStack[stackPtr + 1]) {
+                return true;
+            }
+            return false;
+        };
+
+        // Removes the last state and restores it.
+        this.undo = function () {
+
+            if (undoObj.canUndo()) {
+                if (lastState) {
+                    // What about setting state -1 to null or checking for undefined?
+                    lastState.restore();
+                    lastState = null;
+                }
+                else {
+                    undoStack[stackPtr] = new TextareaState(panels);
+                    undoStack[--stackPtr].restore();
+
+                    if (callback) {
+                        callback();
+                    }
+                }
+            }
+
+            mode = "none";
+            panels.input.focus();
+            refreshState();
+        };
+
+        // Redo an action.
+        this.redo = function () {
+
+            if (undoObj.canRedo()) {
+
+                undoStack[++stackPtr].restore();
+
+                if (callback) {
+                    callback();
+                }
+            }
+
+            mode = "none";
+            panels.input.focus();
+            refreshState();
+        };
+
+        // Push the input area state to the stack.
+        var saveState = function () {
+            var currState = inputStateObj || new TextareaState(panels);
+
+            if (!currState) {
+                return false;
+            }
+            if (mode == "moving") {
+                if (!lastState) {
+                    lastState = currState;
+                }
+                return;
+            }
+            if (lastState) {
+                if (undoStack[stackPtr - 1].text != lastState.text) {
+                    undoStack[stackPtr++] = lastState;
+                }
+                lastState = null;
+            }
+            undoStack[stackPtr++] = currState;
+            undoStack[stackPtr + 1] = null;
+            if (callback) {
+                callback();
+            }
+        };
+
+        var handleCtrlYZ = function (event) {
+
+            var handled = false;
+
+            if ((event.ctrlKey || event.metaKey) && !event.altKey) {
+
+                // IE and Opera do not support charCode.
+                var keyCode = event.charCode || event.keyCode;
+                var keyCodeChar = String.fromCharCode(keyCode);
+
+                switch (keyCodeChar.toLowerCase()) {
+
+                    case "y":
+                        undoObj.redo();
+                        handled = true;
+                        break;
+
+                    case "z":
+                        if (!event.shiftKey) {
+                            undoObj.undo();
+                        }
+                        else {
+                            undoObj.redo();
+                        }
+                        handled = true;
+                        break;
+                }
+            }
+
+            if (handled) {
+                if (event.preventDefault) {
+                    event.preventDefault();
+                }
+                if (window.event) {
+                    window.event.returnValue = false;
+                }
+                return;
+            }
+        };
+
+        // Set the mode depending on what is going on in the input area.
+        var handleModeChange = function (event) {
+
+            if (!event.ctrlKey && !event.metaKey) {
+
+                var keyCode = event.keyCode;
+
+                if ((keyCode >= 33 && keyCode <= 40) || (keyCode >= 63232 && keyCode <= 63235)) {
+                    // 33 - 40: page up/dn and arrow keys
+                    // 63232 - 63235: page up/dn and arrow keys on safari
+                    setMode("moving");
+                }
+                else if (keyCode == 8 || keyCode == 46 || keyCode == 127) {
+                    // 8: backspace
+                    // 46: delete
+                    // 127: delete
+                    setMode("deleting");
+                }
+                else if (keyCode == 13) {
+                    // 13: Enter
+                    setMode("newlines");
+                }
+                else if (keyCode == 27) {
+                    // 27: escape
+                    setMode("escape");
+                }
+                else if ((keyCode < 16 || keyCode > 20) && keyCode != 91) {
+                    // 16-20 are shift, etc.
+                    // 91: left window key
+                    // I think this might be a little messed up since there are
+                    // a lot of nonprinting keys above 20.
+                    setMode("typing");
+                }
+            }
+        };
+
+        var setEventHandlers = function () {
+            util.addEvent(panels.input, "keypress", function (event) {
+                // keyCode 89: y
+                // keyCode 90: z
+                if ((event.ctrlKey || event.metaKey) && !event.altKey && (event.keyCode == 89 || event.keyCode == 90)) {
+                    event.preventDefault();
+                }
+            });
+
+            var handlePaste = function () {
+                if (uaSniffed.isIE || (inputStateObj && inputStateObj.text != panels.input.value)) {
+                    if (timer == undefined) {
+                        mode = "paste";
+                        saveState();
+                        refreshState();
+                    }
+                }
+            };
+
+            util.addEvent(panels.input, "keydown", handleCtrlYZ);
+            util.addEvent(panels.input, "keydown", handleModeChange);
+            util.addEvent(panels.input, "mousedown", function () {
+                setMode("moving");
+            });
+
+            panels.input.onpaste = handlePaste;
+            panels.input.ondrop = handlePaste;
+        };
+
+        var init = function () {
+            setEventHandlers();
+            refreshState(true);
+            saveState();
+        };
+
+        init();
+    }
+
+    // end of UndoManager
+
+    // The input textarea state/contents.
+    // This is used to implement undo/redo by the undo manager.
+    function TextareaState(panels, isInitialState) {
+
+        // Aliases
+        var stateObj = this;
+        var inputArea = panels.input;
+        this.init = function () {
+            if (!util.isVisible(inputArea)) {
+                return;
+            }
+            if (!isInitialState && doc.activeElement && doc.activeElement !== inputArea) { // this happens when tabbing out of the input box
+                return;
+            }
+
+            this.setInputAreaSelectionStartEnd();
+            this.scrollTop = inputArea.scrollTop;
+            if (!this.text && inputArea.selectionStart || inputArea.selectionStart === 0) {
+                this.text = inputArea.value;
+            }
+
+        }
+
+        // Sets the selected text in the input box after we've performed an
+        // operation.
+        this.setInputAreaSelection = function () {
+
+            if (!util.isVisible(inputArea)) {
+                return;
+            }
+
+            if (inputArea.selectionStart !== undefined && !uaSniffed.isOpera) {
+
+                inputArea.focus();
+                inputArea.selectionStart = stateObj.start;
+                inputArea.selectionEnd = stateObj.end;
+                inputArea.scrollTop = stateObj.scrollTop;
+            }
+            else if (doc.selection) {
+
+                if (doc.activeElement && doc.activeElement !== inputArea) {
+                    return;
+                }
+
+                inputArea.focus();
+                var range = inputArea.createTextRange();
+                range.moveStart("character", -inputArea.value.length);
+                range.moveEnd("character", -inputArea.value.length);
+                range.moveEnd("character", stateObj.end);
+                range.moveStart("character", stateObj.start);
+                range.select();
+            }
+        };
+
+        this.setInputAreaSelectionStartEnd = function () {
+
+            if (!panels.ieCachedRange && (inputArea.selectionStart || inputArea.selectionStart === 0)) {
+
+                stateObj.start = inputArea.selectionStart;
+                stateObj.end = inputArea.selectionEnd;
+            }
+            else if (doc.selection) {
+
+                stateObj.text = util.fixEolChars(inputArea.value);
+
+                // IE loses the selection in the textarea when buttons are
+                // clicked.  On IE we cache the selection. Here, if something is cached,
+                // we take it.
+                var range = panels.ieCachedRange || doc.selection.createRange();
+
+                var fixedRange = util.fixEolChars(range.text);
+                var marker = "\x07";
+                var markedRange = marker + fixedRange + marker;
+                range.text = markedRange;
+                var inputText = util.fixEolChars(inputArea.value);
+
+                range.moveStart("character", -markedRange.length);
+                range.text = fixedRange;
+
+                stateObj.start = inputText.indexOf(marker);
+                stateObj.end = inputText.lastIndexOf(marker) - marker.length;
+
+                var len = stateObj.text.length - util.fixEolChars(inputArea.value).length;
+
+                if (len) {
+                    range.moveStart("character", -fixedRange.length);
+                    while (len--) {
+                        fixedRange += "\n";
+                        stateObj.end += 1;
+                    }
+                    range.text = fixedRange;
+                }
+
+                if (panels.ieCachedRange)
+                    stateObj.scrollTop = panels.ieCachedScrollTop; // this is set alongside with ieCachedRange
+
+                panels.ieCachedRange = null;
+
+                this.setInputAreaSelection();
+            }
+        };
+
+        // Restore this state into the input area.
+        this.restore = function () {
+
+            if (stateObj.text != undefined && stateObj.text != inputArea.value) {
+                inputArea.value = stateObj.text;
+            }
+            this.setInputAreaSelection();
+            inputArea.scrollTop = stateObj.scrollTop;
+        };
+
+        // Gets a collection of HTML chunks from the inptut textarea.
+        this.getChunks = function () {
+
+            var chunk = new Chunks();
+            chunk.before = util.fixEolChars(stateObj.text.substring(0, stateObj.start));
+            chunk.startTag = "";
+            chunk.selection = util.fixEolChars(stateObj.text.substring(stateObj.start, stateObj.end));
+            chunk.endTag = "";
+            chunk.after = util.fixEolChars(stateObj.text.substring(stateObj.end));
+            chunk.scrollTop = stateObj.scrollTop;
+
+            return chunk;
+        };
+
+        // Sets the TextareaState properties given a chunk of markdown.
+        this.setChunks = function (chunk) {
+
+            chunk.before = chunk.before + chunk.startTag;
+            chunk.after = chunk.endTag + chunk.after;
+
+            this.start = chunk.before.length;
+            this.end = chunk.before.length + chunk.selection.length;
+            this.text = chunk.before + chunk.selection + chunk.after;
+            this.scrollTop = chunk.scrollTop;
+        };
+        this.init();
+    };
+
+    function PreviewManager(converter, panels, previewRefreshCallback) {
+
+        var managerObj = this;
+        var timeout;
+        var elapsedTime;
+        var oldInputText;
+        var maxDelay = 3000;
+        var startType = "delayed"; // The other legal value is "manual"
+
+        // Adds event listeners to elements
+        var setupEvents = function (inputElem, listener) {
+
+            util.addEvent(inputElem, "input", listener);
+            inputElem.onpaste = listener;
+            inputElem.ondrop = listener;
+
+            util.addEvent(inputElem, "keypress", listener);
+            util.addEvent(inputElem, "keydown", listener);
+        };
+
+        var getDocScrollTop = function () {
+
+            var result = 0;
+
+            if (window.innerHeight) {
+                result = window.pageYOffset;
+            }
+            else
+                if (doc.documentElement && doc.documentElement.scrollTop) {
+                    result = doc.documentElement.scrollTop;
+                }
+                else
+                    if (doc.body) {
+                        result = doc.body.scrollTop;
+                    }
+
+            return result;
+        };
+
+        var makePreviewHtml = function () {
+
+            // If there is no registered preview panel
+            // there is nothing to do.
+            if (!panels.preview)
+                return;
+
+
+            var text = panels.input.value;
+            if (text && text == oldInputText) {
+                return; // Input text hasn't changed.
+            }
+            else {
+                oldInputText = text;
+            }
+
+            var prevTime = new Date().getTime();
+
+            text = converter.makeHtml(text);
+
+            // Calculate the processing time of the HTML creation.
+            // It's used as the delay time in the event listener.
+            var currTime = new Date().getTime();
+            elapsedTime = currTime - prevTime;
+
+            pushPreviewHtml(text);
+        };
+
+        // setTimeout is already used.  Used as an event listener.
+        var applyTimeout = function () {
+
+            if (timeout) {
+                clearTimeout(timeout);
+                timeout = undefined;
+            }
+
+            if (startType !== "manual") {
+
+                var delay = 0;
+
+                if (startType === "delayed") {
+                    delay = elapsedTime;
+                }
+
+                if (delay > maxDelay) {
+                    delay = maxDelay;
+                }
+                timeout = setTimeout(makePreviewHtml, delay);
+            }
+        };
+
+        var getScaleFactor = function (panel) {
+            if (panel.scrollHeight <= panel.clientHeight) {
+                return 1;
+            }
+            return panel.scrollTop / (panel.scrollHeight - panel.clientHeight);
+        };
+
+        var setPanelScrollTops = function () {
+            if (panels.preview) {
+                panels.preview.scrollTop = (panels.preview.scrollHeight - panels.preview.clientHeight) * getScaleFactor(panels.preview);
+            }
+        };
+
+        this.refresh = function (requiresRefresh) {
+
+            if (requiresRefresh) {
+                oldInputText = "";
+                makePreviewHtml();
+            }
+            else {
+                applyTimeout();
+            }
+        };
+
+        this.processingTime = function () {
+            return elapsedTime;
+        };
+
+        var isFirstTimeFilled = true;
+
+        // IE doesn't let you use innerHTML if the element is contained somewhere in a table
+        // (which is the case for inline editing) -- in that case, detach the element, set the
+        // value, and reattach. Yes, that *is* ridiculous.
+        var ieSafePreviewSet = function (text) {
+            var preview = panels.preview;
+            var parent = preview.parentNode;
+            var sibling = preview.nextSibling;
+            parent.removeChild(preview);
+            preview.innerHTML = text;
+            if (!sibling)
+                parent.appendChild(preview);
+            else
+                parent.insertBefore(preview, sibling);
+        }
+
+        var nonSuckyBrowserPreviewSet = function (text) {
+            panels.preview.innerHTML = text;
+        }
+
+        var previewSetter;
+
+        var previewSet = function (text) {
+            if (previewSetter)
+                return previewSetter(text);
+
+            try {
+                nonSuckyBrowserPreviewSet(text);
+                previewSetter = nonSuckyBrowserPreviewSet;
+            } catch (e) {
+                previewSetter = ieSafePreviewSet;
+                previewSetter(text);
+            }
+        };
+
+        var pushPreviewHtml = function (text) {
+
+            var emptyTop = position.getTop(panels.input) - getDocScrollTop();
+
+            if (panels.preview) {
+                previewSet(text);
+                previewRefreshCallback();
+            }
+
+            setPanelScrollTops();
+
+            if (isFirstTimeFilled) {
+                isFirstTimeFilled = false;
+                return;
+            }
+
+            var fullTop = position.getTop(panels.input) - getDocScrollTop();
+
+            if (uaSniffed.isIE) {
+                setTimeout(function () {
+                    window.scrollBy(0, fullTop - emptyTop);
+                }, 0);
+            }
+            else {
+                window.scrollBy(0, fullTop - emptyTop);
+            }
+        };
+
+        var init = function () {
+
+            setupEvents(panels.input, applyTimeout);
+            makePreviewHtml();
+
+            if (panels.preview) {
+                panels.preview.scrollTop = 0;
+            }
+        };
+
+        init();
+    };
+
+    // Creates the background behind the hyperlink text entry box.
+    // And download dialog
+    // Most of this has been moved to CSS but the div creation and
+    // browser-specific hacks remain here.
+    ui.createBackground = function () {
+
+        var background = doc.createElement("div"),
+            style = background.style;
+        
+        background.className = "wmd-prompt-background";
+        
+        style.position = "absolute";
+        style.top = "0";
+
+        style.zIndex = "1000";
+
+        if (uaSniffed.isIE) {
+            style.filter = "alpha(opacity=50)";
+        }
+        else {
+            style.opacity = "0.5";
+        }
+
+        var pageSize = position.getPageSize();
+        style.height = pageSize[1] + "px";
+
+        if (uaSniffed.isIE) {
+            style.left = doc.documentElement.scrollLeft;
+            style.width = doc.documentElement.clientWidth;
+        }
+        else {
+            style.left = "0";
+            style.width = "100%";
+        }
+
+        doc.body.appendChild(background);
+        return background;
+    };
+
+    // This simulates a modal dialog box and asks for the URL when you
+    // click the hyperlink or image buttons.
+    //
+    // text: The html for the input box.
+    // defaultInputText: The default value that appears in the input box.
+    // callback: The function which is executed when the prompt is dismissed, either via OK or Cancel.
+    //      It receives a single argument; either the entered text (if OK was chosen) or null (if Cancel
+    //      was chosen).
+    ui.prompt = function (text, defaultInputText, callback) {
+
+        // These variables need to be declared at this level since they are used
+        // in multiple functions.
+        var dialog;         // The dialog box.
+        var input;         // The text box where you enter the hyperlink.
+
+
+        if (defaultInputText === undefined) {
+            defaultInputText = "";
+        }
+
+        // Used as a keydown event handler. Esc dismisses the prompt.
+        // Key code 27 is ESC.
+        var checkEscape = function (key) {
+            var code = (key.charCode || key.keyCode);
+            if (code === 27) {
+                close(true);
+            }
+        };
+
+        // Dismisses the hyperlink input box.
+        // isCancel is true if we don't care about the input text.
+        // isCancel is false if we are going to keep the text.
+        var close = function (isCancel) {
+            util.removeEvent(doc.body, "keydown", checkEscape);
+            var text = input.value;
+
+            if (isCancel) {
+                text = null;
+            }
+            else {
+                // Fixes common pasting errors.
+                text = text.replace(/^http:\/\/(https?|ftp):\/\//, '$1://');
+                if (!/^(?:https?|ftp):\/\//.test(text))
+                    text = 'http://' + text;
+            }
+
+            dialog.parentNode.removeChild(dialog);
+
+            callback(text);
+            return false;
+        };
+
+
+
+        // Create the text input box form/window.
+        var createDialog = function () {
+
+            // The main dialog box.
+            dialog = doc.createElement("div");
+            dialog.className = "wmd-prompt-dialog";
+            dialog.style.padding = "10px;";
+            dialog.style.position = "fixed";
+            dialog.style.width = "400px";
+            dialog.style.zIndex = "1001";
+
+            // The dialog text.
+            var question = doc.createElement("div");
+            question.innerHTML = text;
+            dialog.appendChild(question);
+
+            // The web form container for the text box and buttons.
+            var form = doc.createElement("form");
+            form.onsubmit = function () { return close(false); };
+            dialog.appendChild(form);
+
+            // The input text box
+            input = doc.createElement("input");
+            input.type = "text";
+            input.value = defaultInputText;
+            style = input.style;
+            style.display = "block";
+            style.width = "80%";
+            style.marginLeft = style.marginRight = "auto";
+            form.appendChild(input);
+
+            // The ok button
+            var okButton = doc.createElement("input");
+            okButton.type = "button";
+            okButton.onclick = function () { return close(false); };
+            okButton.value = "OK";
+            style = okButton.style;
+            style.margin = "10px";
+            style.width = "7em";
+
+
+            // The cancel button
+            var cancelButton = doc.createElement("input");
+            cancelButton.type = "button";
+            cancelButton.onclick = function () { return close(true); };
+            cancelButton.value = "Cancel";
+            style = cancelButton.style;
+            style.margin = "10px";
+            style.display = "inline";
+            style.width = "7em";
+
+            form.appendChild(okButton);
+            form.appendChild(cancelButton);
+
+            util.addEvent(doc.body, "keydown", checkEscape);
+            dialog.style.top = "50%";
+            dialog.style.left = "50%";
+            dialog.style.display = "block";
+            if (uaSniffed.isIE_5or6) {
+                dialog.style.position = "absolute";
+                dialog.style.top = doc.documentElement.scrollTop + 200 + "px";
+                dialog.style.left = "50%";
+            }
+            doc.body.appendChild(dialog);
+
+            // This has to be done AFTER adding the dialog to the form if you
+            // want it to be centered.
+            dialog.style.marginTop = -(position.getHeight(dialog) / 2) + "px";
+            dialog.style.marginLeft = -(position.getWidth(dialog) / 2) + "px";
+
+        };
+
+        // Why is this in a zero-length timeout?
+        // Is it working around a browser bug?
+        setTimeout(function () {
+
+            createDialog();
+
+            var defTextLen = defaultInputText.length;
+            if (input.selectionStart !== undefined) {
+                input.selectionStart = 0;
+                input.selectionEnd = defTextLen;
+            }
+            else if (input.createTextRange) {
+                var range = input.createTextRange();
+                range.collapse(false);
+                range.moveStart("character", -defTextLen);
+                range.moveEnd("character", defTextLen);
+                range.select();
+            }
+
+            input.focus();
+        }, 0);
+    };
+
+    function UIManager(postfix, panels, undoManager, previewManager, commandManager, helpOptions, getString) {
+
+        var inputBox = panels.input,
+            buttons = {}; // buttons.undo, buttons.link, etc. The actual DOM elements.
+
+        makeSpritedButtonRow();
+
+        var keyEvent = "keydown";
+        if (uaSniffed.isOpera) {
+            keyEvent = "keypress";
+        }
+
+        util.addEvent(inputBox, keyEvent, function (key) {
+
+            // Check to see if we have a button key and, if so execute the callback.
+            if ((key.ctrlKey || key.metaKey) && !key.altKey && !key.shiftKey) {
+
+                var keyCode = key.charCode || key.keyCode;
+                var keyCodeStr = String.fromCharCode(keyCode).toLowerCase();
+
+                switch (keyCodeStr) {
+                    case "b":
+                        doClick(buttons.bold);
+                        break;
+                    case "i":
+                        doClick(buttons.italic);
+                        break;
+                    case "l":
+                        doClick(buttons.link);
+                        break;
+                    case "q":
+                        doClick(buttons.quote);
+                        break;
+                    case "k":
+                        doClick(buttons.code);
+                        break;
+                    case "g":
+                        doClick(buttons.image);
+                        break;
+                    case "o":
+                        doClick(buttons.olist);
+                        break;
+                    case "u":
+                        doClick(buttons.ulist);
+                        break;
+                    case "h":
+                        doClick(buttons.heading);
+                        break;
+                    case "r":
+                        doClick(buttons.hr);
+                        break;
+                    case "y":
+                        doClick(buttons.redo);
+                        break;
+                    case "z":
+                        if (key.shiftKey) {
+                            doClick(buttons.redo);
+                        }
+                        else {
+                            doClick(buttons.undo);
+                        }
+                        break;
+                    default:
+                        return;
+                }
+
+
+                if (key.preventDefault) {
+                    key.preventDefault();
+                }
+
+                if (window.event) {
+                    window.event.returnValue = false;
+                }
+            }
+        });
+
+        // Auto-indent on shift-enter
+        util.addEvent(inputBox, "keyup", function (key) {
+            if (key.shiftKey && !key.ctrlKey && !key.metaKey) {
+                var keyCode = key.charCode || key.keyCode;
+                // Character 13 is Enter
+                if (keyCode === 13) {
+                    var fakeButton = {};
+                    fakeButton.textOp = bindCommand("doAutoindent");
+                    doClick(fakeButton);
+                }
+            }
+        });
+
+        // special handler because IE clears the context of the textbox on ESC
+        if (uaSniffed.isIE) {
+            util.addEvent(inputBox, "keydown", function (key) {
+                var code = key.keyCode;
+                if (code === 27) {
+                    return false;
+                }
+            });
+        }
+
+
+        // Perform the button's action.
+        function doClick(button) {
+
+            inputBox.focus();
+
+            if (button.textOp) {
+
+                if (undoManager) {
+                    undoManager.setCommandMode();
+                }
+
+                var state = new TextareaState(panels);
+
+                if (!state) {
+                    return;
+                }
+
+                var chunks = state.getChunks();
+
+                // Some commands launch a "modal" prompt dialog.  Javascript
+                // can't really make a modal dialog box and the WMD code
+                // will continue to execute while the dialog is displayed.
+                // This prevents the dialog pattern I'm used to and means
+                // I can't do something like this:
+                //
+                // var link = CreateLinkDialog();
+                // makeMarkdownLink(link);
+                //
+                // Instead of this straightforward method of handling a
+                // dialog I have to pass any code which would execute
+                // after the dialog is dismissed (e.g. link creation)
+                // in a function parameter.
+                //
+                // Yes this is awkward and I think it sucks, but there's
+                // no real workaround.  Only the image and link code
+                // create dialogs and require the function pointers.
+                var fixupInputArea = function () {
+
+                    inputBox.focus();
+
+                    if (chunks) {
+                        state.setChunks(chunks);
+                    }
+
+                    state.restore();
+                    previewManager.refresh();
+                };
+
+                var noCleanup = button.textOp(chunks, fixupInputArea);
+
+                if (!noCleanup) {
+                    fixupInputArea();
+                }
+
+            }
+
+            if (button.execute) {
+                button.execute(undoManager);
+            }
+        };
+
+        function setupButton(button, isEnabled) {
+
+            var normalYShift = "0px";
+            var disabledYShift = "-20px";
+            var highlightYShift = "-40px";
+            var image = button.getElementsByTagName("span")[0];
+            if (isEnabled) {
+                image.style.backgroundPosition = button.XShift + " " + normalYShift;
+                button.onmouseover = function () {
+                    image.style.backgroundPosition = this.XShift + " " + highlightYShift;
+                };
+
+                button.onmouseout = function () {
+                    image.style.backgroundPosition = this.XShift + " " + normalYShift;
+                };
+
+                // IE tries to select the background image "button" text (it's
+                // implemented in a list item) so we have to cache the selection
+                // on mousedown.
+                if (uaSniffed.isIE) {
+                    button.onmousedown = function () {
+                        if (doc.activeElement && doc.activeElement !== panels.input) { // we're not even in the input box, so there's no selection
+                            return;
+                        }
+                        panels.ieCachedRange = document.selection.createRange();
+                        panels.ieCachedScrollTop = panels.input.scrollTop;
+                    };
+                }
+
+                if (!button.isHelp) {
+                    button.onclick = function () {
+                        if (this.onmouseout) {
+                            this.onmouseout();
+                        }
+                        doClick(this);
+                        return false;
+                    }
+                }
+            }
+            else {
+                image.style.backgroundPosition = button.XShift + " " + disabledYShift;
+                button.onmouseover = button.onmouseout = button.onclick = function () { };
+            }
+        }
+
+        function bindCommand(method) {
+            if (typeof method === "string")
+                method = commandManager[method];
+            return function () { method.apply(commandManager, arguments); }
+        }
+
+        function makeSpritedButtonRow() {
+
+            var buttonBar = panels.buttonBar;
+
+            var normalYShift = "0px";
+            var disabledYShift = "-20px";
+            var highlightYShift = "-40px";
+
+            var buttonRow = document.createElement("ul");
+            buttonRow.id = "wmd-button-row" + postfix;
+            buttonRow.className = 'wmd-button-row';
+            buttonRow = buttonBar.appendChild(buttonRow);
+            var xPosition = 0;
+            var makeButton = function (id, title, XShift, textOp) {
+                var button = document.createElement("li");
+                button.className = "wmd-button";
+                button.style.left = xPosition + "px";
+                xPosition += 25;
+                var buttonImage = document.createElement("span");
+                button.id = id + postfix;
+                button.appendChild(buttonImage);
+                button.title = title;
+                button.XShift = XShift;
+                if (textOp)
+                    button.textOp = textOp;
+                setupButton(button, true);
+                buttonRow.appendChild(button);
+                return button;
+            };
+            var makeSpacer = function (num) {
+                var spacer = document.createElement("li");
+                spacer.className = "wmd-spacer wmd-spacer" + num;
+                spacer.id = "wmd-spacer" + num + postfix;
+                buttonRow.appendChild(spacer);
+                xPosition += 25;
+            }
+
+            buttons.bold = makeButton("wmd-bold-button", getString("bold"), "0px", bindCommand("doBold"));
+            buttons.italic = makeButton("wmd-italic-button", getString("italic"), "-20px", bindCommand("doItalic"));
+            makeSpacer(1);
+            buttons.link = makeButton("wmd-link-button", getString("link"), "-40px", bindCommand(function (chunk, postProcessing) {
+                return this.doLinkOrImage(chunk, postProcessing, false);
+            }));
+            buttons.quote = makeButton("wmd-quote-button", getString("quote"), "-60px", bindCommand("doBlockquote"));
+            buttons.code = makeButton("wmd-code-button", getString("code"), "-80px", bindCommand("doCode"));
+            buttons.image = makeButton("wmd-image-button", getString("image"), "-100px", bindCommand(function (chunk, postProcessing) {
+                return this.doLinkOrImage(chunk, postProcessing, true);
+            }));
+            makeSpacer(2);
+            buttons.olist = makeButton("wmd-olist-button", getString("olist"), "-120px", bindCommand(function (chunk, postProcessing) {
+                this.doList(chunk, postProcessing, true);
+            }));
+            buttons.ulist = makeButton("wmd-ulist-button", getString("ulist"), "-140px", bindCommand(function (chunk, postProcessing) {
+                this.doList(chunk, postProcessing, false);
+            }));
+            buttons.heading = makeButton("wmd-heading-button", getString("heading"), "-160px", bindCommand("doHeading"));
+            buttons.hr = makeButton("wmd-hr-button", getString("hr"), "-180px", bindCommand("doHorizontalRule"));
+            makeSpacer(3);
+            buttons.undo = makeButton("wmd-undo-button", getString("undo"), "-200px", null);
+            buttons.undo.execute = function (manager) { if (manager) manager.undo(); };
+
+            var redoTitle = /win/.test(nav.platform.toLowerCase()) ?
+                getString("redo") :
+                getString("redomac"); // mac and other non-Windows platforms
+
+            buttons.redo = makeButton("wmd-redo-button", redoTitle, "-220px", null);
+            buttons.redo.execute = function (manager) { if (manager) manager.redo(); };
+
+            if (helpOptions) {
+                var helpButton = document.createElement("li");
+                var helpButtonImage = document.createElement("span");
+                helpButton.appendChild(helpButtonImage);
+                helpButton.className = "wmd-button wmd-help-button";
+                helpButton.id = "wmd-help-button" + postfix;
+                helpButton.XShift = "-240px";
+                helpButton.isHelp = true;
+                helpButton.style.right = "0px";
+                helpButton.title = getString("help");
+                helpButton.onclick = helpOptions.handler;
+
+                setupButton(helpButton, true);
+                buttonRow.appendChild(helpButton);
+                buttons.help = helpButton;
+            }
+
+            setUndoRedoButtonStates();
+        }
+
+        function setUndoRedoButtonStates() {
+            if (undoManager) {
+                setupButton(buttons.undo, undoManager.canUndo());
+                setupButton(buttons.redo, undoManager.canRedo());
+            }
+        };
+
+        this.setUndoRedoButtonStates = setUndoRedoButtonStates;
+
+    }
+
+    function CommandManager(pluginHooks, getString) {
+        this.hooks = pluginHooks;
+        this.getString = getString;
+    }
+
+    var commandProto = CommandManager.prototype;
+
+    // The markdown symbols - 4 spaces = code, > = blockquote, etc.
+    commandProto.prefixes = "(?:\\s{4,}|\\s*>|\\s*-\\s+|\\s*\\d+\\.|=|\\+|-|_|\\*|#|\\s*\\[[^\n]]+\\]:)";
+
+    // Remove markdown symbols from the chunk selection.
+    commandProto.unwrap = function (chunk) {
+        var txt = new re("([^\\n])\\n(?!(\\n|" + this.prefixes + "))", "g");
+        chunk.selection = chunk.selection.replace(txt, "$1 $2");
+    };
+
+    commandProto.wrap = function (chunk, len) {
+        this.unwrap(chunk);
+        var regex = new re("(.{1," + len + "})( +|$\\n?)", "gm"),
+            that = this;
+
+        chunk.selection = chunk.selection.replace(regex, function (line, marked) {
+            if (new re("^" + that.prefixes, "").test(line)) {
+                return line;
+            }
+            return marked + "\n";
+        });
+
+        chunk.selection = chunk.selection.replace(/\s+$/, "");
+    };
+
+    commandProto.doBold = function (chunk, postProcessing) {
+        return this.doBorI(chunk, postProcessing, 2, this.getString("boldexample"));
+    };
+
+    commandProto.doItalic = function (chunk, postProcessing) {
+        return this.doBorI(chunk, postProcessing, 1, this.getString("italicexample"));
+    };
+
+    // chunk: The selected region that will be enclosed with */**
+    // nStars: 1 for italics, 2 for bold
+    // insertText: If you just click the button without highlighting text, this gets inserted
+    commandProto.doBorI = function (chunk, postProcessing, nStars, insertText) {
+
+        // Get rid of whitespace and fixup newlines.
+        chunk.trimWhitespace();
+        chunk.selection = chunk.selection.replace(/\n{2,}/g, "\n");
+
+        // Look for stars before and after.  Is the chunk already marked up?
+        // note that these regex matches cannot fail
+        var starsBefore = /(\**$)/.exec(chunk.before)[0];
+        var starsAfter = /(^\**)/.exec(chunk.after)[0];
+
+        var prevStars = Math.min(starsBefore.length, starsAfter.length);
+
+        // Remove stars if we have to since the button acts as a toggle.
+        if ((prevStars >= nStars) && (prevStars != 2 || nStars != 1)) {
+            chunk.before = chunk.before.replace(re("[*]{" + nStars + "}$", ""), "");
+            chunk.after = chunk.after.replace(re("^[*]{" + nStars + "}", ""), "");
+        }
+        else if (!chunk.selection && starsAfter) {
+            // It's not really clear why this code is necessary.  It just moves
+            // some arbitrary stuff around.
+            chunk.after = chunk.after.replace(/^([*_]*)/, "");
+            chunk.before = chunk.before.replace(/(\s?)$/, "");
+            var whitespace = re.$1;
+            chunk.before = chunk.before + starsAfter + whitespace;
+        }
+        else {
+
+            // In most cases, if you don't have any selected text and click the button
+            // you'll get a selected, marked up region with the default text inserted.
+            if (!chunk.selection && !starsAfter) {
+                chunk.selection = insertText;
+            }
+
+            // Add the true markup.
+            var markup = nStars <= 1 ? "*" : "**"; // shouldn't the test be = ?
+            chunk.before = chunk.before + markup;
+            chunk.after = markup + chunk.after;
+        }
+
+        return;
+    };
+
+    commandProto.stripLinkDefs = function (text, defsToAdd) {
+
+        text = text.replace(/^[ ]{0,3}\[(\d+)\]:[ \t]*\n?[ \t]*?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+|$)/gm,
+            function (totalMatch, id, link, newlines, title) {
+                defsToAdd[id] = totalMatch.replace(/\s*$/, "");
+                if (newlines) {
+                    // Strip the title and return that separately.
+                    defsToAdd[id] = totalMatch.replace(/["(](.+?)[")]$/, "");
+                    return newlines + title;
+                }
+                return "";
+            });
+
+        return text;
+    };
+
+    commandProto.addLinkDef = function (chunk, linkDef) {
+
+        var refNumber = 0; // The current reference number
+        var defsToAdd = {}; //
+        // Start with a clean slate by removing all previous link definitions.
+        chunk.before = this.stripLinkDefs(chunk.before, defsToAdd);
+        chunk.selection = this.stripLinkDefs(chunk.selection, defsToAdd);
+        chunk.after = this.stripLinkDefs(chunk.after, defsToAdd);
+
+        var defs = "";
+        var regex = /(\[)((?:\[[^\]]*\]|[^\[\]])*)(\][ ]?(?:\n[ ]*)?\[)(\d+)(\])/g;
+
+        var addDefNumber = function (def) {
+            refNumber++;
+            def = def.replace(/^[ ]{0,3}\[(\d+)\]:/, "  [" + refNumber + "]:");
+            defs += "\n" + def;
+        };
+
+        // note that
+        // a) the recursive call to getLink cannot go infinite, because by definition
+        //    of regex, inner is always a proper substring of wholeMatch, and
+        // b) more than one level of nesting is neither supported by the regex
+        //    nor making a lot of sense (the only use case for nesting is a linked image)
+        var getLink = function (wholeMatch, before, inner, afterInner, id, end) {
+            inner = inner.replace(regex, getLink);
+            if (defsToAdd[id]) {
+                addDefNumber(defsToAdd[id]);
+                return before + inner + afterInner + refNumber + end;
+            }
+            return wholeMatch;
+        };
+
+        chunk.before = chunk.before.replace(regex, getLink);
+
+        if (linkDef) {
+            addDefNumber(linkDef);
+        }
+        else {
+            chunk.selection = chunk.selection.replace(regex, getLink);
+        }
+
+        var refOut = refNumber;
+
+        chunk.after = chunk.after.replace(regex, getLink);
+
+        if (chunk.after) {
+            chunk.after = chunk.after.replace(/\n*$/, "");
+        }
+        if (!chunk.after) {
+            chunk.selection = chunk.selection.replace(/\n*$/, "");
+        }
+
+        chunk.after += "\n\n" + defs;
+
+        return refOut;
+    };
+
+    // takes the line as entered into the add link/as image dialog and makes
+    // sure the URL and the optinal title are "nice".
+    function properlyEncoded(linkdef) {
+        return linkdef.replace(/^\s*(.*?)(?:\s+"(.+)")?\s*$/, function (wholematch, link, title) {
+            link = link.replace(/\?.*$/, function (querypart) {
+                return querypart.replace(/\+/g, " "); // in the query string, a plus and a space are identical
+            });
+            link = decodeURIComponent(link); // unencode first, to prevent double encoding
+            link = encodeURI(link).replace(/'/g, '%27').replace(/\(/g, '%28').replace(/\)/g, '%29');
+            link = link.replace(/\?.*$/, function (querypart) {
+                return querypart.replace(/\+/g, "%2b"); // since we replaced plus with spaces in the query part, all pluses that now appear where originally encoded
+            });
+            if (title) {
+                title = title.trim ? title.trim() : title.replace(/^\s*/, "").replace(/\s*$/, "");
+                title = title.replace(/"/g, "quot;").replace(/\(/g, "(").replace(/\)/g, ")").replace(//g, ">");
+            }
+            return title ? link + ' "' + title + '"' : link;
+        });
+    }
+
+    commandProto.doLinkOrImage = function (chunk, postProcessing, isImage) {
+
+        chunk.trimWhitespace();
+        chunk.findTags(/\s*!?\[/, /\][ ]?(?:\n[ ]*)?(\[.*?\])?/);
+        var background;
+
+        if (chunk.endTag.length > 1 && chunk.startTag.length > 0) {
+
+            chunk.startTag = chunk.startTag.replace(/!?\[/, "");
+            chunk.endTag = "";
+            this.addLinkDef(chunk, null);
+
+        }
+        else {
+            
+            // We're moving start and end tag back into the selection, since (as we're in the else block) we're not
+            // *removing* a link, but *adding* one, so whatever findTags() found is now back to being part of the
+            // link text. linkEnteredCallback takes care of escaping any brackets.
+            chunk.selection = chunk.startTag + chunk.selection + chunk.endTag;
+            chunk.startTag = chunk.endTag = "";
+
+            if (/\n\n/.test(chunk.selection)) {
+                this.addLinkDef(chunk, null);
+                return;
+            }
+            var that = this;
+            // The function to be executed when you enter a link and press OK or Cancel.
+            // Marks up the link and adds the ref.
+            var linkEnteredCallback = function (link) {
+
+                background.parentNode.removeChild(background);
+
+                if (link !== null) {
+                    // (                          $1
+                    //     [^\\]                  anything that's not a backslash
+                    //     (?:\\\\)*              an even number (this includes zero) of backslashes
+                    // )
+                    // (?=                        followed by
+                    //     [[\]]                  an opening or closing bracket
+                    // )
+                    //
+                    // In other words, a non-escaped bracket. These have to be escaped now to make sure they
+                    // don't count as the end of the link or similar.
+                    // Note that the actual bracket has to be a lookahead, because (in case of to subsequent brackets),
+                    // the bracket in one match may be the "not a backslash" character in the next match, so it
+                    // should not be consumed by the first match.
+                    // The "prepend a space and finally remove it" steps makes sure there is a "not a backslash" at the
+                    // start of the string, so this also works if the selection begins with a bracket. We cannot solve
+                    // this by anchoring with ^, because in the case that the selection starts with two brackets, this
+                    // would mean a zero-width match at the start. Since zero-width matches advance the string position,
+                    // the first bracket could then not act as the "not a backslash" for the second.
+                    chunk.selection = (" " + chunk.selection).replace(/([^\\](?:\\\\)*)(?=[[\]])/g, "$1\\").substr(1);
+                    
+                    var linkDef = " [999]: " + properlyEncoded(link);
+
+                    var num = that.addLinkDef(chunk, linkDef);
+                    chunk.startTag = isImage ? "![" : "[";
+                    chunk.endTag = "][" + num + "]";
+
+                    if (!chunk.selection) {
+                        if (isImage) {
+                            chunk.selection = that.getString("imagedescription");
+                        }
+                        else {
+                            chunk.selection = that.getString("linkdescription");
+                        }
+                    }
+                }
+                postProcessing();
+            };
+
+            background = ui.createBackground();
+
+            if (isImage) {
+                if (!this.hooks.insertImageDialog(linkEnteredCallback))
+                    ui.prompt(this.getString("imagedialog"), imageDefaultText, linkEnteredCallback);
+            }
+            else {
+                ui.prompt(this.getString("linkdialog"), linkDefaultText, linkEnteredCallback);
+            }
+            return true;
+        }
+    };
+
+    // When making a list, hitting shift-enter will put your cursor on the next line
+    // at the current indent level.
+    commandProto.doAutoindent = function (chunk, postProcessing) {
+
+        var commandMgr = this,
+            fakeSelection = false;
+
+        chunk.before = chunk.before.replace(/(\n|^)[ ]{0,3}([*+-]|\d+[.])[ \t]*\n$/, "\n\n");
+        chunk.before = chunk.before.replace(/(\n|^)[ ]{0,3}>[ \t]*\n$/, "\n\n");
+        chunk.before = chunk.before.replace(/(\n|^)[ \t]+\n$/, "\n\n");
+        
+        // There's no selection, end the cursor wasn't at the end of the line:
+        // The user wants to split the current list item / code line / blockquote line
+        // (for the latter it doesn't really matter) in two. Temporarily select the
+        // (rest of the) line to achieve this.
+        if (!chunk.selection && !/^[ \t]*(?:\n|$)/.test(chunk.after)) {
+            chunk.after = chunk.after.replace(/^[^\n]*/, function (wholeMatch) {
+                chunk.selection = wholeMatch;
+                return "";
+            });
+            fakeSelection = true;
+        }
+
+        if (/(\n|^)[ ]{0,3}([*+-]|\d+[.])[ \t]+.*\n$/.test(chunk.before)) {
+            if (commandMgr.doList) {
+                commandMgr.doList(chunk);
+            }
+        }
+        if (/(\n|^)[ ]{0,3}>[ \t]+.*\n$/.test(chunk.before)) {
+            if (commandMgr.doBlockquote) {
+                commandMgr.doBlockquote(chunk);
+            }
+        }
+        if (/(\n|^)(\t|[ ]{4,}).*\n$/.test(chunk.before)) {
+            if (commandMgr.doCode) {
+                commandMgr.doCode(chunk);
+            }
+        }
+        
+        if (fakeSelection) {
+            chunk.after = chunk.selection + chunk.after;
+            chunk.selection = "";
+        }
+    };
+
+    commandProto.doBlockquote = function (chunk, postProcessing) {
+
+        chunk.selection = chunk.selection.replace(/^(\n*)([^\r]+?)(\n*)$/,
+            function (totalMatch, newlinesBefore, text, newlinesAfter) {
+                chunk.before += newlinesBefore;
+                chunk.after = newlinesAfter + chunk.after;
+                return text;
+            });
+
+        chunk.before = chunk.before.replace(/(>[ \t]*)$/,
+            function (totalMatch, blankLine) {
+                chunk.selection = blankLine + chunk.selection;
+                return "";
+            });
+
+        chunk.selection = chunk.selection.replace(/^(\s|>)+$/, "");
+        chunk.selection = chunk.selection || this.getString("quoteexample");
+
+        // The original code uses a regular expression to find out how much of the
+        // text *directly before* the selection already was a blockquote:
+
+        /*
+        if (chunk.before) {
+        chunk.before = chunk.before.replace(/\n?$/, "\n");
+        }
+        chunk.before = chunk.before.replace(/(((\n|^)(\n[ \t]*)*>(.+\n)*.*)+(\n[ \t]*)*$)/,
+        function (totalMatch) {
+        chunk.startTag = totalMatch;
+        return "";
+        });
+        */
+
+        // This comes down to:
+        // Go backwards as many lines a possible, such that each line
+        //  a) starts with ">", or
+        //  b) is almost empty, except for whitespace, or
+        //  c) is preceeded by an unbroken chain of non-empty lines
+        //     leading up to a line that starts with ">" and at least one more character
+        // and in addition
+        //  d) at least one line fulfills a)
+        //
+        // Since this is essentially a backwards-moving regex, it's susceptible to
+        // catstrophic backtracking and can cause the browser to hang;
+        // see e.g. http://meta.stackoverflow.com/questions/9807.
+        //
+        // Hence we replaced this by a simple state machine that just goes through the
+        // lines and checks for a), b), and c).
+
+        var match = "",
+            leftOver = "",
+            line;
+        if (chunk.before) {
+            var lines = chunk.before.replace(/\n$/, "").split("\n");
+            var inChain = false;
+            for (var i = 0; i < lines.length; i++) {
+                var good = false;
+                line = lines[i];
+                inChain = inChain && line.length > 0; // c) any non-empty line continues the chain
+                if (/^>/.test(line)) {                // a)
+                    good = true;
+                    if (!inChain && line.length > 1)  // c) any line that starts with ">" and has at least one more character starts the chain
+                        inChain = true;
+                } else if (/^[ \t]*$/.test(line)) {   // b)
+                    good = true;
+                } else {
+                    good = inChain;                   // c) the line is not empty and does not start with ">", so it matches if and only if we're in the chain
+                }
+                if (good) {
+                    match += line + "\n";
+                } else {
+                    leftOver += match + line;
+                    match = "\n";
+                }
+            }
+            if (!/(^|\n)>/.test(match)) {             // d)
+                leftOver += match;
+                match = "";
+            }
+        }
+
+        chunk.startTag = match;
+        chunk.before = leftOver;
+
+        // end of change
+
+        if (chunk.after) {
+            chunk.after = chunk.after.replace(/^\n?/, "\n");
+        }
+
+        chunk.after = chunk.after.replace(/^(((\n|^)(\n[ \t]*)*>(.+\n)*.*)+(\n[ \t]*)*)/,
+            function (totalMatch) {
+                chunk.endTag = totalMatch;
+                return "";
+            }
+        );
+
+        var replaceBlanksInTags = function (useBracket) {
+
+            var replacement = useBracket ? "> " : "";
+
+            if (chunk.startTag) {
+                chunk.startTag = chunk.startTag.replace(/\n((>|\s)*)\n$/,
+                    function (totalMatch, markdown) {
+                        return "\n" + markdown.replace(/^[ ]{0,3}>?[ \t]*$/gm, replacement) + "\n";
+                    });
+            }
+            if (chunk.endTag) {
+                chunk.endTag = chunk.endTag.replace(/^\n((>|\s)*)\n/,
+                    function (totalMatch, markdown) {
+                        return "\n" + markdown.replace(/^[ ]{0,3}>?[ \t]*$/gm, replacement) + "\n";
+                    });
+            }
+        };
+
+        if (/^(?![ ]{0,3}>)/m.test(chunk.selection)) {
+            this.wrap(chunk, SETTINGS.lineLength - 2);
+            chunk.selection = chunk.selection.replace(/^/gm, "> ");
+            replaceBlanksInTags(true);
+            chunk.skipLines();
+        } else {
+            chunk.selection = chunk.selection.replace(/^[ ]{0,3}> ?/gm, "");
+            this.unwrap(chunk);
+            replaceBlanksInTags(false);
+
+            if (!/^(\n|^)[ ]{0,3}>/.test(chunk.selection) && chunk.startTag) {
+                chunk.startTag = chunk.startTag.replace(/\n{0,2}$/, "\n\n");
+            }
+
+            if (!/(\n|^)[ ]{0,3}>.*$/.test(chunk.selection) && chunk.endTag) {
+                chunk.endTag = chunk.endTag.replace(/^\n{0,2}/, "\n\n");
+            }
+        }
+
+        chunk.selection = this.hooks.postBlockquoteCreation(chunk.selection);
+
+        if (!/\n/.test(chunk.selection)) {
+            chunk.selection = chunk.selection.replace(/^(> *)/,
+            function (wholeMatch, blanks) {
+                chunk.startTag += blanks;
+                return "";
+            });
+        }
+    };
+
+    commandProto.doCode = function (chunk, postProcessing) {
+
+        var hasTextBefore = /\S[ ]*$/.test(chunk.before);
+        var hasTextAfter = /^[ ]*\S/.test(chunk.after);
+
+        // Use 'four space' markdown if the selection is on its own
+        // line or is multiline.
+        if ((!hasTextAfter && !hasTextBefore) || /\n/.test(chunk.selection)) {
+
+            chunk.before = chunk.before.replace(/[ ]{4}$/,
+                function (totalMatch) {
+                    chunk.selection = totalMatch + chunk.selection;
+                    return "";
+                });
+
+            var nLinesBack = 1;
+            var nLinesForward = 1;
+
+            if (/(\n|^)(\t|[ ]{4,}).*\n$/.test(chunk.before)) {
+                nLinesBack = 0;
+            }
+            if (/^\n(\t|[ ]{4,})/.test(chunk.after)) {
+                nLinesForward = 0;
+            }
+
+            chunk.skipLines(nLinesBack, nLinesForward);
+
+            if (!chunk.selection) {
+                chunk.startTag = "    ";
+                chunk.selection = this.getString("codeexample");
+            }
+            else {
+                if (/^[ ]{0,3}\S/m.test(chunk.selection)) {
+                    if (/\n/.test(chunk.selection))
+                        chunk.selection = chunk.selection.replace(/^/gm, "    ");
+                    else // if it's not multiline, do not select the four added spaces; this is more consistent with the doList behavior
+                        chunk.before += "    ";
+                }
+                else {
+                    chunk.selection = chunk.selection.replace(/^(?:[ ]{4}|[ ]{0,3}\t)/gm, "");
+                }
+            }
+        }
+        else {
+            // Use backticks (`) to delimit the code block.
+
+            chunk.trimWhitespace();
+            chunk.findTags(/`/, /`/);
+
+            if (!chunk.startTag && !chunk.endTag) {
+                chunk.startTag = chunk.endTag = "`";
+                if (!chunk.selection) {
+                    chunk.selection = this.getString("codeexample");
+                }
+            }
+            else if (chunk.endTag && !chunk.startTag) {
+                chunk.before += chunk.endTag;
+                chunk.endTag = "";
+            }
+            else {
+                chunk.startTag = chunk.endTag = "";
+            }
+        }
+    };
+
+    commandProto.doList = function (chunk, postProcessing, isNumberedList) {
+
+        // These are identical except at the very beginning and end.
+        // Should probably use the regex extension function to make this clearer.
+        var previousItemsRegex = /(\n|^)(([ ]{0,3}([*+-]|\d+[.])[ \t]+.*)(\n.+|\n{2,}([*+-].*|\d+[.])[ \t]+.*|\n{2,}[ \t]+\S.*)*)\n*$/;
+        var nextItemsRegex = /^\n*(([ ]{0,3}([*+-]|\d+[.])[ \t]+.*)(\n.+|\n{2,}([*+-].*|\d+[.])[ \t]+.*|\n{2,}[ \t]+\S.*)*)\n*/;
+
+        // The default bullet is a dash but others are possible.
+        // This has nothing to do with the particular HTML bullet,
+        // it's just a markdown bullet.
+        var bullet = "-";
+
+        // The number in a numbered list.
+        var num = 1;
+
+        // Get the item prefix - e.g. " 1. " for a numbered list, " - " for a bulleted list.
+        var getItemPrefix = function () {
+            var prefix;
+            if (isNumberedList) {
+                prefix = " " + num + ". ";
+                num++;
+            }
+            else {
+                prefix = " " + bullet + " ";
+            }
+            return prefix;
+        };
+
+        // Fixes the prefixes of the other list items.
+        var getPrefixedItem = function (itemText) {
+
+            // The numbering flag is unset when called by autoindent.
+            if (isNumberedList === undefined) {
+                isNumberedList = /^\s*\d/.test(itemText);
+            }
+
+            // Renumber/bullet the list element.
+            itemText = itemText.replace(/^[ ]{0,3}([*+-]|\d+[.])\s/gm,
+                function (_) {
+                    return getItemPrefix();
+                });
+
+            return itemText;
+        };
+
+        chunk.findTags(/(\n|^)*[ ]{0,3}([*+-]|\d+[.])\s+/, null);
+
+        if (chunk.before && !/\n$/.test(chunk.before) && !/^\n/.test(chunk.startTag)) {
+            chunk.before += chunk.startTag;
+            chunk.startTag = "";
+        }
+
+        if (chunk.startTag) {
+
+            var hasDigits = /\d+[.]/.test(chunk.startTag);
+            chunk.startTag = "";
+            chunk.selection = chunk.selection.replace(/\n[ ]{4}/g, "\n");
+            this.unwrap(chunk);
+            chunk.skipLines();
+
+            if (hasDigits) {
+                // Have to renumber the bullet points if this is a numbered list.
+                chunk.after = chunk.after.replace(nextItemsRegex, getPrefixedItem);
+            }
+            if (isNumberedList == hasDigits) {
+                return;
+            }
+        }
+
+        var nLinesUp = 1;
+
+        chunk.before = chunk.before.replace(previousItemsRegex,
+            function (itemText) {
+                if (/^\s*([*+-])/.test(itemText)) {
+                    bullet = re.$1;
+                }
+                nLinesUp = /[^\n]\n\n[^\n]/.test(itemText) ? 1 : 0;
+                return getPrefixedItem(itemText);
+            });
+
+        if (!chunk.selection) {
+            chunk.selection = this.getString("litem");
+        }
+
+        var prefix = getItemPrefix();
+
+        var nLinesDown = 1;
+
+        chunk.after = chunk.after.replace(nextItemsRegex,
+            function (itemText) {
+                nLinesDown = /[^\n]\n\n[^\n]/.test(itemText) ? 1 : 0;
+                return getPrefixedItem(itemText);
+            });
+
+        chunk.trimWhitespace(true);
+        chunk.skipLines(nLinesUp, nLinesDown, true);
+        chunk.startTag = prefix;
+        var spaces = prefix.replace(/./g, " ");
+        this.wrap(chunk, SETTINGS.lineLength - spaces.length);
+        chunk.selection = chunk.selection.replace(/\n/g, "\n" + spaces);
+
+    };
+
+    commandProto.doHeading = function (chunk, postProcessing) {
+
+        // Remove leading/trailing whitespace and reduce internal spaces to single spaces.
+        chunk.selection = chunk.selection.replace(/\s+/g, " ");
+        chunk.selection = chunk.selection.replace(/(^\s+|\s+$)/g, "");
+
+        // If we clicked the button with no selected text, we just
+        // make a level 2 hash header around some default text.
+        if (!chunk.selection) {
+            chunk.startTag = "## ";
+            chunk.selection = this.getString("headingexample");
+            chunk.endTag = " ##";
+            return;
+        }
+
+        var headerLevel = 0;     // The existing header level of the selected text.
+
+        // Remove any existing hash heading markdown and save the header level.
+        chunk.findTags(/#+[ ]*/, /[ ]*#+/);
+        if (/#+/.test(chunk.startTag)) {
+            headerLevel = re.lastMatch.length;
+        }
+        chunk.startTag = chunk.endTag = "";
+
+        // Try to get the current header level by looking for - and = in the line
+        // below the selection.
+        chunk.findTags(null, /\s?(-+|=+)/);
+        if (/=+/.test(chunk.endTag)) {
+            headerLevel = 1;
+        }
+        if (/-+/.test(chunk.endTag)) {
+            headerLevel = 2;
+        }
+
+        // Skip to the next line so we can create the header markdown.
+        chunk.startTag = chunk.endTag = "";
+        chunk.skipLines(1, 1);
+
+        // We make a level 2 header if there is no current header.
+        // If there is a header level, we substract one from the header level.
+        // If it's already a level 1 header, it's removed.
+        var headerLevelToCreate = headerLevel == 0 ? 2 : headerLevel - 1;
+
+        if (headerLevelToCreate > 0) {
+
+            // The button only creates level 1 and 2 underline headers.
+            // Why not have it iterate over hash header levels?  Wouldn't that be easier and cleaner?
+            var headerChar = headerLevelToCreate >= 2 ? "-" : "=";
+            var len = chunk.selection.length;
+            if (len > SETTINGS.lineLength) {
+                len = SETTINGS.lineLength;
+            }
+            chunk.endTag = "\n";
+            while (len--) {
+                chunk.endTag += headerChar;
+            }
+        }
+    };
+
+    commandProto.doHorizontalRule = function (chunk, postProcessing) {
+        chunk.startTag = "----------\n";
+        chunk.selection = "";
+        chunk.skipLines(2, 1, true);
+    }
+
+
+})();
diff --git a/media/js/Markdown.Extra.js b/media/js/Markdown.Extra.js
new file mode 100644
index 0000000000..3124907321
--- /dev/null
+++ b/media/js/Markdown.Extra.js
@@ -0,0 +1,593 @@
+(function () {
+  // A quick way to make sure we're only keeping span-level tags when we need to.
+  // This isn't supposed to be foolproof. It's just a quick way to make sure we
+  // keep all span-level tags returned by a pagedown converter. It should allow
+  // all span-level tags through, with or without attributes.
+  var inlineTags = new RegExp(['^(<\\/?(a|abbr|acronym|applet|area|b|basefont|',
+                               'bdo|big|button|cite|code|del|dfn|em|figcaption|',
+                               'font|i|iframe|img|input|ins|kbd|label|map|',
+                               'mark|meter|object|param|progress|q|ruby|rp|rt|s|',
+                               'samp|script|select|small|span|strike|strong|',
+                               'sub|sup|textarea|time|tt|u|var|wbr)[^>]*>|',
+                               '<(br)\\s?\\/?>)$'].join(''), 'i');
+
+  /******************************************************************
+   * Utility Functions                                              *
+   *****************************************************************/
+
+  function trim(str) {
+    return str.replace(/^\s+|\s+$/g, '');
+  }
+
+  function rtrim(str) {
+    return str.replace(/\s+$/g, '');
+  }
+
+  // Remove one level of indentation from text. Indent is 4 spaces.
+  function outdent(text) {
+      return text.replace(new RegExp('^(\\t|[ ]{1,4})', 'gm'), '');
+  }
+
+  function contains(str, substr) {
+    return str.indexOf(substr) != -1;
+  }
+
+  // Sanitize html, removing tags that aren't in the whitelist
+  function sanitizeHtml(html, whitelist) {
+    return html.replace(/<[^>]*>?/gi, function(tag) {
+      return tag.match(whitelist) ? tag : '';
+    });
+  }
+
+  // Merge two arrays, keeping only unique elements.
+  function union(x, y) {
+    var obj = {};
+    for (var i = 0; i < x.length; i++)
+       obj[x[i]] = x[i];
+    for (i = 0; i < y.length; i++)
+       obj[y[i]] = y[i];
+    var res = [];
+    for (var k in obj) {
+      if (obj.hasOwnProperty(k))
+        res.push(obj[k]);
+    }
+    return res;
+  }
+
+  // JS regexes don't support \A or \Z, so we add sentinels, as Pagedown
+  // does. In this case, we add the ascii codes for start of text (STX) and
+  // end of text (ETX), an idea borrowed from:
+  // https://github.com/tanakahisateru/js-markdown-extra
+  function addAnchors(text) {
+    if(text.charAt(0) != '\x02')
+      text = '\x02' + text;
+    if(text.charAt(text.length - 1) != '\x03')
+      text = text + '\x03';
+    return text;
+  }
+
+  // Remove STX and ETX sentinels.
+  function removeAnchors(text) {
+    if(text.charAt(0) == '\x02')
+      text = text.substr(1);
+    if(text.charAt(text.length - 1) == '\x03')
+      text = text.substr(0, text.length - 1);
+    return text;
+  }
+
+  // Convert markdown within an element, retaining only span-level tags
+  // (An inefficient version of Pagedown's runSpanGamut. We rely on a
+  // pagedown coverter to do the complete conversion, and then retain
+  // only the specified tags -- inline in this case).
+  function convertSpans(text, converter) {
+    text = denormalize(text);
+    var html = converter.makeHtml(text);
+    return sanitizeHtml(html, inlineTags);
+  }
+
+  // Convert internal markdown using the stock pagedown converter
+  function convertAll(text, converter) {
+    text = denormalize(text);
+    return converter.makeHtml(text);
+  }
+
+  // We use convertSpans and convertAll to convert markdown inside of Markdown Extra
+  // elements we create. Since this markdown has already been through the pagedown
+  // normalization process before our hooks were called, we need to do some
+  // denormalization before sending it back through a different Pagedown converter.
+  function denormalize(text) {
+    // Restore dollar signs and tildes
+    text = text.replace(/~D/g, "$$");
+    text = text.replace(/~T/g, "~");
+    return text;
+  }
+
+  // Convert escaped special characters to HTML decimal entity codes.
+  function processEscapes(text) {
+    // Markdown extra adds two escapable characters, `:` and `|`
+    // If escaped, we convert them to html entities so our
+    // regexes don't recognize them. Markdown doesn't support escaping
+    // the escape character, e.g. `\\`, which make this even simpler.
+    return text.replace(/\\\|/g, '|').replace(/\\:/g, ':');
+  }
+
+  // Determine if the given pagedown converter performs sanitization
+  // on postConversion
+  function isSanitizing(converter) {
+    // call the converter's postConversion hook and see if it sanitizes its input
+    return converter.hooks.postConversion("") === "";
+  }
+
+
+  /******************************************************************
+   * Markdown.Extra                                                 *
+   *****************************************************************/
+
+  Markdown.Extra = function() {
+    // For converting internal markdown (in tables for instance).
+    // This is necessary since these methods are meant to be called as
+    // preConversion hooks, and the Markdown converter passed to init()
+    // won't convert any markdown contained in the html tags we return.
+    this.converter = null;
+
+    // Stores html blocks we generate in hooks so that
+    // they're not destroyed if the user is using a sanitizing converter
+    this.hashBlocks = [];
+
+    // Special attribute blocks for fenced code blocks and headers enabled.
+    this.attributeBlocks = false;
+
+    // Fenced code block options
+    this.googleCodePrettify = false;
+    this.highlightJs = false;
+
+    // Table options
+    this.tableClass = '';
+
+    this.tabWidth = 4;
+  };
+
+  Markdown.Extra.init = function(converter, options) {
+    // Each call to init creates a new instance of Markdown.Extra so it's
+    // safe to have multiple converters, with different options, on a single page
+    var extra = new Markdown.Extra();
+    var transformations = [];
+
+    options = options || {};
+    options.extensions = options.extensions || ["all"];
+    if (contains(options.extensions, "all")) {
+      transformations.push("all");
+      extra.attributeBlocks = true;
+    } else {
+      if (contains(options.extensions, "tables"))
+        transformations.push("tables");
+      if (contains(options.extensions, "fenced_code_gfm"))
+        transformations.push("fencedCodeBlocks");
+      if (contains(options.extensions, "def_list"))
+        transformations.push("definitionLists");
+      if (contains(options.extensions, "attr_list"))
+        extra.attributeBlocks = true;
+    }
+
+    // preBlockGamut also gives us access to a hook so we can run the
+    // block gamut recursively, however we don't need it at this point
+    converter.hooks.chain("preBlockGamut", function(text) {
+      return extra.doConversion(transformations, text);
+    });
+
+    converter.hooks.chain("postConversion", function(text) {
+      return extra.finishConversion(text);
+    });
+
+    if ("highlighter" in options) {
+      extra.googleCodePrettify = options.highlighter === 'prettify';
+      extra.highlightJs = options.highlighter === 'highlight';
+    }
+
+    if ("table_class" in options) {
+      extra.tableClass = options.table_class;
+    }
+
+    // we can't just use the same converter that the user passes in, as
+    // Pagedown forbids it (doing so could cause an infinite loop)
+    extra.converter = isSanitizing(converter) ? Markdown.getSanitizingConverter()
+                                              : new Markdown.Converter();
+
+    // Caller usually won't need this, but it's handy for testing.
+    return extra;
+  };
+
+  // Setup state vars, do conversion
+  Markdown.Extra.prototype.doConversion = function(transformations, text) {
+    this.hashBlocks = [];
+
+    text = processEscapes(text);
+
+    if (this.attributeBlocks)
+      text = this.hashAttributeBlocks(text);
+
+    for(var i = 0; i < transformations.length; i++)
+      text = this[transformations[i]](text);
+
+    return text + '\n';
+  };
+
+  // Clear state vars that may use unnecessary memory. Unhash blocks we
+  // stored, apply attribute blocks if necessary, and return converted text.
+  Markdown.Extra.prototype.finishConversion = function(text) {
+    text = this.unHashExtraBlocks(text);
+
+    if (this.attributeBlocks)
+      text = this.applyAttributeBlocks(text);
+
+    this.hashBlocks = [];
+    return text;
+  };
+
+  // Return a placeholder containing a key, which is the block's index in the
+  // hashBlocks array. We wrap our output in a 
         tag here so Pagedown won't.
+  Markdown.Extra.prototype.hashExtraBlock = function(block) {
+    return '\n
        ~X' + (this.hashBlocks.push(block) - 1) + 'X
        \n';
+  };
+
+  // Replace placeholder blocks in `text` with their corresponding
+  // html blocks in the hashBlocks array.
+  Markdown.Extra.prototype.unHashExtraBlocks = function(text) {
+    var self = this;
+    text = text.replace(/
        ~X(\d+)X<\/p>/g, function(wholeMatch, m1) {
+      var key = parseInt(m1, 10);
+      return self.hashBlocks[key];
+    });
+    return text;
+  };
+
+
+  /******************************************************************
+   * Attribute Blocks                                               *
+   *****************************************************************/
+
+  // Extract attribute blocks, move them above the element they will be
+  // applied to, and hash them for later.
+  Markdown.Extra.prototype.hashAttributeBlocks = function(text) {
+    // TODO: use sentinels. Should we just add/remove them in doConversion?
+    // TODO: better matches for id / class attributes
+    var attrBlock = "\\{\\s*[.|#][^}]+\\}";
+    var hdrAttributesA = new RegExp("^(#{1,6}.*\\s*#{0,6})\\s+(" + attrBlock + ")\\s*(\\n|0x03)", "gm");
+    var hdrAttributesB = new RegExp("^(.*\\s.*)\\s+(" + attrBlock + ")\\s*\\n" +
+                                    "(?=[\\-|=]+\\s*(\\n|0x03))", "gm"); // underline lookahead
+    var fcbAttributes =  new RegExp("^(```[^{]*)\\s+(" + attrBlock + ")\\s*\\n" +
+                                    "(?=([\\s\\S]*?)\\n```\\s*(\\n|0x03))", "gm");
+
+    var self = this;
+    function attributeCallback(wholeMatch, pre, attr) {
+      return '
        ~XX' + (self.hashBlocks.push(attr) - 1) + 'XX
        \n' + pre + "\n";
+    }
+
+    text = text.replace(hdrAttributesA, attributeCallback);  // ## headers
+    text = text.replace(hdrAttributesB, attributeCallback);  // underline headers
+    return text.replace(fcbAttributes, attributeCallback);
+  };
+
+  Markdown.Extra.prototype.applyAttributeBlocks = function(text) {
+    var self = this;
+    var blockRe = new RegExp('
        ~XX(\\d+)XX
        [\\s\\S]*' +
+                             '(?:<(h[1-6]|pre)(?: +class="(\\S+)")?(>[\\s\\S]*))', "gm");
+    text = text.replace(blockRe, function(wholeMatch, k, tag, cls, rest) {
+      if (!tag) // no following header or fenced code block.
+        return '';
+
+      // get attributes list from hash
+      var key = parseInt(k, 10);
+      var attributes = self.hashBlocks[key];
+
+      // get id
+      var id = attributes.match(/#[^\s{}]+/g) || [];
+      var idStr = id[0] ? ' id="' + id[0].substr(1, id[0].length - 1) + '"' : '';
+
+      // get classes and merge with existing classes
+      var classes = attributes.match(/\.[^\s{}]+/g) || [];
+      for (var i = 0; i < classes.length; i++) // Remove leading dot
+        classes[i] = classes[i].substr(1, classes[i].length - 1);
+
+      var classStr = '';
+      if (cls)
+        classes = union(classes, [cls]);
+
+      if (classes.length > 0)
+        classStr = ' class="' + classes.join(' ') + '"';
+
+      return "<" + tag + idStr + classStr + rest;
+    });
+
+    return text;
+  };
+
+  /******************************************************************
+   * Tables                                                         *
+   *****************************************************************/
+
+  // Find and convert Markdown Extra tables into html.
+  Markdown.Extra.prototype.tables = function(text) {
+    var self = this;
+
+    var leadingPipe = new RegExp(
+      ['^'                         ,
+       '[ ]{0,3}'                  , // Allowed whitespace
+       '[|]'                       , // Initial pipe
+       '(.+)\\n'                   , // $1: Header Row
+
+       '[ ]{0,3}'                  , // Allowed whitespace
+       '[|]([ ]*[-:]+[-| :]*)\\n'  , // $2: Separator
+
+       '('                         , // $3: Table Body
+         '(?:[ ]*[|].*\\n?)*'      , // Table rows
+       ')',
+       '(?:\\n|$)'                   // Stop at final newline
+      ].join(''),
+      'gm'
+    );
+
+    var noLeadingPipe = new RegExp(
+      ['^'                         ,
+       '[ ]{0,3}'                  , // Allowed whitespace
+       '(\\S.*[|].*)\\n'           , // $1: Header Row
+
+       '[ ]{0,3}'                  , // Allowed whitespace
+       '([-:]+[ ]*[|][-| :]*)\\n'  , // $2: Separator
+
+       '('                         , // $3: Table Body
+         '(?:.*[|].*\\n?)*'        , // Table rows
+       ')'                         ,
+       '(?:\\n|$)'                   // Stop at final newline
+      ].join(''),
+      'gm'
+    );
+
+    text = text.replace(leadingPipe, doTable);
+    text = text.replace(noLeadingPipe, doTable);
+
+    // $1 = header, $2 = separator, $3 = body
+    function doTable(match, header, separator, body, offset, string) {
+      // remove any leading pipes and whitespace
+      header = header.replace(/^ *[|]/m, '');
+      separator = separator.replace(/^ *[|]/m, '');
+      body = body.replace(/^ *[|]/gm, '');
+
+      // remove trailing pipes and whitespace
+      header = header.replace(/[|] *$/m, '');
+      separator = separator.replace(/[|] *$/m, '');
+      body = body.replace(/[|] *$/gm, '');
+
+      // determine column alignments
+      alignspecs = separator.split(/ *[|] */);
+      align = [];
+      for (var i = 0; i < alignspecs.length; i++) {
+        var spec = alignspecs[i];
+        if (spec.match(/^ *-+: *$/m))
+          align[i] = ' style="text-align:right;"';
+        else if (spec.match(/^ *:-+: *$/m))
+          align[i] = ' style="text-align:center;"';
+        else if (spec.match(/^ *:-+ *$/m))
+          align[i] = ' style="text-align:left;"';
+        else align[i] = '';
+      }
+
+      // TODO: parse spans in header and rows before splitting, so that pipes
+      // inside of tags are not interpreted as separators
+      var headers = header.split(/ *[|] */);
+      var colCount = headers.length;
+
+      // build html
+      var cls = self.tableClass ? ' class="' + self.tableClass + '"' : '';
+      var html = ['\n', '\n', '\n'].join('');
+
+      // build column headers.
+      for (i = 0; i < colCount; i++) {
+        var headerHtml = convertSpans(trim(headers[i]), self.converter);
+        html += ["  ", headerHtml, "\n"].join('');
+      }
+      html += "\n\n";
+
+      // build rows
+      var rows = body.split('\n');
+      for (i = 0; i < rows.length; i++) {
+        if (rows[i].match(/^\s*$/)) // can apply to final row
+          continue;
+
+        // ensure number of rowCells matches colCount
+        var rowCells = rows[i].split(/ *[|] */);
+        var lenDiff = colCount - rowCells.length;
+        for (var j = 0; j < lenDiff; j++)
+          rowCells.push('');
+
+        html += "\n";
+        for (j = 0; j < colCount; j++) {
+          var colHtml = convertSpans(trim(rowCells[j]), self.converter);
+          html += ["  ", colHtml, "\n"].join('');
+        }
+        html += "\n";
+      }
+
+      html += "
        \n";
+
+      // replace html with placeholder until postConversion step
+      return self.hashExtraBlock(html);
+    }
+
+    return text;
+  };
+
+
+  /******************************************************************
+  * Fenced Code Blocks  (gfm)                                       *
+  ******************************************************************/
+
+  // Find and convert gfm-inspired fenced code blocks into html.
+  Markdown.Extra.prototype.fencedCodeBlocks = function(text) {
+    function encodeCode(code) {
+      code = code.replace(/&/g, "&");
+      code = code.replace(//g, ">");
+      return code;
+    }
+
+    var self = this;
+    text = text.replace(/(?:^|\n)```(.*)\n([\s\S]*?)\n```/g, function(match, m1, m2) {
+      var language = m1, codeblock = m2;
+
+      // adhere to specified options
+      var preclass = self.googleCodePrettify ? ' class="prettyprint"' : '';
+      var codeclass = '';
+      if (language) {
+        if (self.googleCodePrettify || self.highlightJs) {
+          // use html5 language- class names. supported by both prettify and highlight.js
+          codeclass = ' class="language-' + language + '"';
+        } else {
+          codeclass = ' class="' + language + '"';
+        }
+      }
+
+      var html = ['',
+                  encodeCode(codeblock), '
    '].join('');
+
+      // replace codeblock with placeholder until postConversion step
+      return self.hashExtraBlock(html);
+    });
+
+    return text;
+  };
+
+  Markdown.Extra.prototype.all = function(text) {
+    text = this.tables(text);
+    text = this.fencedCodeBlocks(text);
+    return text;
+  };
+
+
+  /******************************************************************
+  * Definition Lists                                                *
+  ******************************************************************/
+
+  // Find and convert markdown extra definition lists into html.
+  Markdown.Extra.prototype.definitionLists = function(text) {
+    var wholeList = new RegExp(
+      ['(\\x02\\n?|\\n\\n)'          ,
+       '(?:'                         ,
+         '('                         , // $1 = whole list
+           '('                       , // $2
+             '[ ]{0,3}'              ,
+             '((?:[ \\t]*\\S.*\\n)+)', // $3 = defined term
+             '\\n?'                  ,
+             '[ ]{0,3}:[ ]+'         , // colon starting definition
+           ')'                       ,
+           '([\\s\\S]+?)'            ,
+           '('                       , // $4
+               '(?=\\0x03)'          , // \z
+             '|'                     ,
+               '(?='                 ,
+                 '\\n{2,}'           ,
+                 '(?=\\S)'           ,
+                 '(?!'               , // Negative lookahead for another term
+                   '[ ]{0,3}'        ,
+                   '(?:\\S.*\\n)+?'  , // defined term
+                   '\\n?'            ,
+                   '[ ]{0,3}:[ ]+'   , // colon starting definition
+                 ')'                 ,
+                 '(?!'               , // Negative lookahead for another definition
+                   '[ ]{0,3}:[ ]+'   , // colon starting definition
+                 ')'                 ,
+               ')'                   ,
+           ')'                       ,
+         ')'                         ,
+       ')'
+      ].join(''),
+      'gm'
+    );
+
+    var self = this;
+    text = addAnchors(text);
+
+    text = text.replace(wholeList, function(match, pre, list) {
+      var result = trim(self.processDefListItems(list));
+      result = "
    \n" + result + "\n
    ";
+      return pre + self.hashExtraBlock(result) + "\n\n";
+    });
+
+    return removeAnchors(text);
+  };
+
+  // Process the contents of a single definition list, splitting it
+  // into individual term and definition list items.
+  Markdown.Extra.prototype.processDefListItems = function(listStr) {
+    var self = this;
+
+    var dt = new RegExp(
+      ['(\\x02\\n?|\\n\\n+)'    , // leading line
+       '('                      , // definition terms = $1
+         '[ ]{0,3}'             , // leading whitespace
+         '(?![:][ ]|[ ])'       , // negative lookahead for a definition
+                                  //   mark (colon) or more whitespace
+         '(?:\\S.*\\n)+?'       , // actual term (not whitespace)
+       ')'                      ,
+       '(?=\\n?[ ]{0,3}:[ ])'     // lookahead for following line feed
+      ].join(''),                 //   with a definition mark
+      'gm'
+    );
+
+    var dd = new RegExp(
+      ['\\n(\\n+)?'              , // leading line = $1
+       '('                       , // marker space = $2
+         '[ ]{0,3}'              , // whitespace before colon
+         '[:][ ]+'               , // definition mark (colon)
+       ')'                       ,
+       '([\\s\\S]+?)'            , // definition text = $3
+       '(?=\\n*'                 , // stop at next definition mark,
+         '(?:'                   , // next term or end of text
+           '\\n[ ]{0,3}[:][ ]|'  ,
+           '
    |\\x03'          , // \z
+         ')'                     ,
+       ')'
+      ].join(''),
+      'gm'
+    );
+
+    listStr = addAnchors(listStr);
+    // trim trailing blank lines:
+    listStr = listStr.replace(/\n{2,}(?=\\x03)/, "\n");
+
+    // Process definition terms.
+    listStr = listStr.replace(dt, function(match, pre, termsStr) {
+      var terms = trim(termsStr).split("\n");
+      var text = '';
+      for (var i = 0; i < terms.length; i++) {
+        var term = terms[i];
+        // process spans inside dt
+        term = convertSpans(trim(term), self.converter);
+        text += "\n
    " + term + "
    ";
+      }
+      return text + "\n";
+    });
+
+    // Process actual definitions.
+    listStr = listStr.replace(dd, function(match, leadingLine, markerSpace, def) {
+      if (leadingLine || def.match(/\n{2,}/)) {
+        // replace marker with the appropriate whitespace indentation
+        def = Array(markerSpace.length + 1).join(' ') + def;
+        // process markdown inside definition
+        // TODO?: currently doesn't apply extensions
+        def = outdent(def) + "\n\n";
+        def = "\n" + convertAll(def, self.converter) + "\n";
+      } else {
+        // convert span-level markdown inside definition
+        def = rtrim(def);
+        def = convertSpans(outdent(def), self.converter);
+      }
+
+      return "\n
    " + def + "
    \n";
+    });
+
+    return removeAnchors(listStr);
+  };
+
+})();
+
diff --git a/media/js/Markdown.Sanitizer.js b/media/js/Markdown.Sanitizer.js
new file mode 100644
index 0000000000..cc5826fa8f
--- /dev/null
+++ b/media/js/Markdown.Sanitizer.js
@@ -0,0 +1,108 @@
+(function () {
+    var output, Converter;
+    if (typeof exports === "object" && typeof require === "function") { // we're in a CommonJS (e.g. Node.js) module
+        output = exports;
+        Converter = require("./Markdown.Converter").Converter;
+    } else {
+        output = window.Markdown;
+        Converter = output.Converter;
+    }
+        
+    output.getSanitizingConverter = function () {
+        var converter = new Converter();
+        converter.hooks.chain("postConversion", sanitizeHtml);
+        converter.hooks.chain("postConversion", balanceTags);
+        return converter;
+    }
+
+    function sanitizeHtml(html) {
+        return html.replace(/<[^>]*>?/gi, sanitizeTag);
+    }
+
+    // (tags that can be opened/closed) | (tags that stand alone)
+    var basic_tag_whitelist = /^(<\/?(b|blockquote|code|del|dd|dl|dt|em|h1|h2|h3|i|kbd|li|ol|p|pre|s|sup|sub|strong|strike|ul)>|<(br|hr)\s?\/?>)$/i;
+    //     |
+    var a_white = /^(]+")?\s?>|<\/a>)$/i;
+
+    // ]*")?(\stitle="[^"<>]*")?\s?\/?>)$/i;
+
+    function sanitizeTag(tag) {
+        if (tag.match(basic_tag_whitelist) || tag.match(a_white) || tag.match(img_white))
+            return tag;
+        else
+            return "";
+    }
+
+    /// 
+    /// attempt to balance HTML tags in the html string
+    /// by removing any unmatched opening or closing tags
+    /// IMPORTANT: we *assume* HTML has *already* been 
+    /// sanitized and is safe/sane before balancing!
+    /// 
+    /// adapted from CODESNIPPET: A8591DBA-D1D3-11DE-947C-BA5556D89593
+    /// 
+    function balanceTags(html) {
+
+        if (html == "")
+            return "";
+
+        var re = /<\/?\w+[^>]*(\s|$|>)/g;
+        // convert everything to lower case; this makes
+        // our case insensitive comparisons easier
+        var tags = html.toLowerCase().match(re);
+
+        // no HTML tags present? nothing to do; exit now
+        var tagcount = (tags || []).length;
+        if (tagcount == 0)
+            return html;
+
+        var tagname, tag;
+        var ignoredtags = "

  • ";
+        var match;
+        var tagpaired = [];
+        var tagremove = [];
+        var needsRemoval = false;
+
+        // loop through matched tags in forward order
+        for (var ctag = 0; ctag < tagcount; ctag++) {
+            tagname = tags[ctag].replace(/<\/?(\w+).*/, "$1");
+            // skip any already paired tags
+            // and skip tags in our ignore list; assume they're self-closed
+            if (tagpaired[ctag] || ignoredtags.search("<" + tagname + ">") > -1)
+                continue;
+
+            tag = tags[ctag];
+            match = -1;
+
+            if (!/^<\//.test(tag)) {
+                // this is an opening tag
+                // search forwards (next tags), look for closing tags
+                for (var ntag = ctag + 1; ntag < tagcount; ntag++) {
+                    if (!tagpaired[ntag] && tags[ntag] == "") {
+                        match = ntag;
+                        break;
+                    }
+                }
+            }
+
+            if (match == -1)
+                needsRemoval = tagremove[ctag] = true; // mark for removal
+            else
+                tagpaired[match] = true; // mark paired
+        }
+
+        if (!needsRemoval)
+            return html;
+
+        // delete all orphaned tags from the string
+
+        var ctag = 0;
+        html = html.replace(re, function (match) {
+            var res = tagremove[ctag] ? "" : match;
+            ctag++;
+            return res;
+        });
+        return html;
+    }
+})();
diff --git a/templates/file_edit.html b/templates/file_edit.html
index 311e5c6c51..66c91156d4 100644
--- a/templates/file_edit.html
+++ b/templates/file_edit.html
@@ -4,19 +4,23 @@
 {% block extra_style %}
 {% if filetype == 'Sf' %}
 
-{% else %}
+{% endif %}
+{% if filetype == 'Text' %}
 
 
 
 {% endif %}
+{% if filetype == 'Markdown' %}
+
+
+{% endif %}