A memory leak which was fixed in the upstream gtk2 version 2.10.7 (Fedora developement) is still present in FC6 - gtk2 version 2.10.4-10.fc6. Application with frequent display update (an in particular style change) consume more and more memory. The two relevant patches are attached, and the memory leak disappears after using them.
Created attachment 146279 [details] Patch from the upstream gtk2 version
Created attachment 146280 [details] second patch that fixes the memory leak
Fixed in the gtk version that is currently in updates-testing. I'll push it to final soon.
Should go out today.