Hi,
I know its not the original topic but as the thread turn to a discussion about gimp I thougth I would post it here.
While browsing a bit around I just found a plugin for the windows version of GIMP which merges the GIMP windows into one big background window.
I haven't tried it for myself but will do it in a moment.

Here is the link:
http://registry.gimp.org/plugin?id=3892