Surfing the Fedora projects site on fedora.redhat.com (the Artwork), I realized that the availabe Fedora art RPM was version 0.96-1, newer than the one I had on my FC1 installation. So I did download and install it. I think it was since then that I now have a white progress bar on rhgb (it's hard to see it), a white background bar on the Gnome menu highlighting the selected white ink row (instead of the normal blue one, it's impossible to read the menu line), different separators on that menu, different handles on the applications menubars and Gnome panels...
The choosen theme is Bluecurve, with Bluecurve controls/windows borders/icons. My other box with FC2-test3 also has redhat-artwork-0.96-1 installed, and the theme is normal.
Did anyone experience such a confusion in themes? Any ideas what may be causing such phenomenon?