I used GIMP exclusively between 1999 and about 2009. There was always something coming in the next version that would fix GIMP. Color profiling, single window, better text tools, etc. They never did. GIMP doesn't even bother subscribing to GNOME's HIG. It's cast adrift in the world of Linux, and after a decade of using it I'm now happily on Pixelmator on OS X.
As far as I know (and I've lurking on the gimp developer list for 10+ years), GIMP has never been a GNOME application. So, from that point of view, there's no particular reason to expect it to conform to GNOME's human-interface guidelines, is there?
It uses the same crappy GTK file mgt widget design philosophy as GNOME.
http://en.wikipedia.org/wiki/GTK%2B GTK is the GIMP toolkit, and GTK is run by the GNOME foundation. There's quite a bit of relationship between GTK/GIMP/GNOME, even if it may be mostly historical these days.
I've always considered GIMP to be a GNOME app, and most people I know have.
I used GIMP exclusively between 1999 and about 2009. There was always something coming in the next version that would fix GIMP. Color profiling, single window, better text tools, etc. They never did. GIMP doesn't even bother subscribing to GNOME's HIG. It's cast adrift in the world of Linux, and after a decade of using it I'm now happily on Pixelmator on OS X.