cssed is a GTK2 application to help create and maintain CSS style sheets 
for web developing.cssed is a small developer editor and validator, that 
tries to ease the CSS editing. 

It features syntax highlighting, syntax validation, MDI notebook based 
interface, quick CSS properties and values insertion, auto-completion 
and dialog-based insertion of CSS complex values.

Being a CSS editor, it's not limited to this language. cssed haved some 
support for HTML (with embbeded Javascript), XML, Javascript, Java, PHP, 
JSP, C, C++, Apache configuration files, .htaccess, Python, Perl, SQL, 
SH and other languages so it can serve quite well as multi-purpose editor.

It can be extended through plugins and scripted with Python, so it's 
quite easy to extend its functionality. The plugins are available from the 
cssed website.