You will be able to use an editor (accessible from the extension button) from CodeMirror, which has nice syntax highlighter. Script and CSS are applied after the page is loaded (document.onload event).
JScript tricks is cross-platform and it works on Mac OS X, Windows and Linux.
NOTE: To install the JScript tricks extension, drag and drop the downloaded .crx file onto the Chrome Extensions window.
Here are some key features of "JScript tricks":
· Automatic JQuery injection
· popup to quick edit and apply tricks or selected text only
· Autostart option
· Default script for all pages
· nice options interface
· JQuery help
· Ctrl+S support
· Ctrl+Alt+H for hidden tricks
· Google Chrome