Nowadays, wxWidgets 3.x already have wxStyledTextCtrl component as regular (not contributed) item.
Unfortunately, there is still no stable version of Code::Blocks for modern wx, right?
So, I decided to update the wxSmith plugin from "Someone else".
It is now can be built both on Windows and Linux.
It allows design wx-3.x.x applications with wxStyledTextCtrl component from within Code::Blocks
built against wx-2.8.12.
I aware about wxSmithSTC pugin shipped with C::B source, but
in my opinion, the "Someone else" variant is better,
because it directly exposes the wxStyledTextCtrl interface available in wx itself, making resulting code more uniform
between different wx-RAD tools (wxFormBuilder for example),
thus making future maintanance of code easier.
Link:
http://www.mediafire.com/download/xumv7nh9z5mguti/wxSmithStc-2.0.zip