dottoro

Dottoro Highlighter plugin is based on the <a href="http://tools.dottoro.com/services/highlighter/docs/plugins.php" rel="nofollow ugc">Dottoro Syntax Highlighter</a> service that provides professional coloring for CSS, HTML, JavaScript and XML languages. 
It supports highlighting CSS, JavaScript and XML blocks embedded into HTML documents, optionally selectable line numbering and buttons for copying and printing code snippets. 
It performs a detailed lexical analysis on the source code and attaches different style classes for different language items, thus providing a very flexible way to modify the appearance of the highlighted code.
Using of the Dottoro Highlighter plugin is really simple. Just insert your code snippet in the Visual or HTML view, select it and press the Dr-Highlight button on the toolbar. 
You don’t need to embed your source code into an element (such as PRE), just select the whole source that you want to highlight and press the Dr-Highlight button. 
Clicking on the Dr-Highlight button pops up a dialog box where you can specify the settings for the highlighted code. 
If you need to modify the appearance of a previously highlighted code, click into it then click on the Dr-Highlight button on the toolbar.
The default settings for the Dottoro Highlighter plugin can be set on the preferences page. 
For further description, please visit the <a href="http://tools.dottoro.com/highlighter/" rel="nofollow ugc">Dottoro Syntax Highlighter</a> site.

Dottoro Syntax Highlighter

Colorize your source code as easily as possible. Dottoro Highlighter provides professional coloring for CSS, HTML, JavaScript and XML languages.

edik

If FacadeX is active, the public WordPress sites are sent with the xhtml mime type. The internal sites like the administration panel and the login screen, which have many xhtml syntax errors, are still sent with the standard mime type.
You must ensure that your public sites have valid XHTML, otherwise you will get parsing errors in your browser.

FacadeX

Sends public sites with the XHTML mime type. The internal sites, which have many XHTML errors, are still sent with the HTML mime type.

Dottoro Syntax Highlighter vs FacadeX