Hello,
I had to fiddle with a number of issues delaying the advancement in the project.

1. GDK/GTK+ is not thread aware under Win32
2. Polling a file descriptor under Win32 does not work using VC++2008 since GLib is compiled against msvcrt.dll and it’s almost impossible to convince VC++2008 to do so
3. GTK+ 2.18.5/Cairo has a bug on Win32 giving an incorrect Windows GDI device context for a drawing area

To continue with the project I gave up inter-thread messaging  and sacrificed the separate grabber-thread. Polling frames from the camera is now done in the idle callback of the main loop and only saving data is done in a separate thread. This should still be a sufficient task splitting on a two core processor to achieve seamless captures at high framerates.
Reverting back to GTK+ 2.16.6 fixed the window DC bug. OK, time to move on with the actual tool development, I still don’t regret not using MFC
Overall CPU utilisation looks good running the tool at 60fps, performance should be ok. I changed the provisional GUI to a one window look:

Cheers, Oliver