In short, it uses a idGLDrawableMaterial widget that calls
renderSystem->BeginFrame(w, h); (with w and h being small for the texture
preview window) and BeginFrame() sets glConfig.vidWidth and vidHeight to
w/h and that never got reset to the original value (window width/height).
This breaks everything because for some reason
renderSystem->GetSCreenWidth()/Height() return glConfig.vidWidth/Height
so it will just continue to render everything at that resolution (in a
small rectangle on the lower left corner of the window).
This bug has already existed in Doom3 1.3.1 (but was less noticable because
apparently when switching away from Doom3 and back to the window it reset
vidWidth/Height to the window resolution)
I only implemented a workaround (restore glConfig.vid* after rendering the
texture preview), it's possible that the same issue exists in other
(probably editor-) code - but a "proper fix" might also break code (and I'm
not super-familiar with the editor code or even just using them)
Editor also seems to start, didn't test much further.
Only tested 32bit Windows, I fear the editor code isn't 64bit clean..
I hope I haven't broken anything elsewhere..
