This feature is already implemented (partly). It is possible to completely override the Syntax Hilighting of the editor. Grab the syntax definition files at
http://horuside.recursivebytes.com/downloads/SyntaxDefinitions.rar, unpack them, edit the Color-Definitions (on top or bottom of the file) to match your SED-style and put them into c:\program files\Horus IDE\xshd\
The directory xshd does not exist, you have to create it. If Horus finds there a syntax definition it will load and use it instead of the built in versions. The scheme of the filenames specify which Language and Visual Style will be overridden. Changing the whole appearance (colors and style of menus, etc) is not possible at the moment.
I plan to improve the appearance in Version 2.3 (make it more lightweight and modern). By doing this I will at least add a method to modify the existing themes (like the syntax definitions).
