Made working example of mixing IndieLib with native OS GUI.
It is possible thanks to existing SDL's hack which allows to say to SDL to use existing window handle for video initialization.
Also I had to build IndieLib with the window centering feature turned off (I just commented code line with SetWindowPos. Can we make something out to provide the control to window centering from the outside of IND_Window class, Javier?)
Here is a demo app: (code requires a compiled QT lib to be built)
7-Zip archive (5MB)
ZIP archive (8MB)
Screenshot
I have some small troubles with input focus distribution, but I think this can be solved.
I will try to make an util to help compile animations and collisions xml files to fully test the possibilities of mixing very rich QT controls library with IndieLib.
[UPD] Qt debug dlls included into archive.
[UPD] Fixed bug in SDL_1.2 for WINDOW_ID hack, all modules are free from external visual studio 2008 run-time libraries. QT is used only in Debug mode to test the process of enabling editing controls in development version and auto removing them in release version.