Will be very nice to replace textarea on "Try it yourself" pages on Ace editor.
Demo: http://ace.c9.io/build/kitchen-sink.html
Some of options:
– Syntax highlighted editor;
– Themes;
– Highlight errors for HTML,CSS,JS,PHP,...;
– Emmet;
– Find/Replace by text/regexp
– and more.
Keyboard Shortcuts: https://github.com/ajaxorg/ace/wiki/Default-Keyboard-Shortcuts
Simple variant: http://jsfiddle.net/ertutggz/5/