Comment 18 for bug 520118

I can confirm that downgrading to the version of libgtk that shipped as an upgrade to karmic (vers. libgtk2.0-0_2.18.3-1ubuntu2.2_amd64.deb ) fixes the issue on my Lucid Xubuntu 64 bit install (kernel 2.6.32-19). After downgrading the issue is remedied in pcmanfm but not in thunar but the downgrade breaks functionality in a ton of other packages so this simply confirms in my mind that the problem exists in libgtk. Unfortunately I cannot keep this older package because a ton of other packages depend on the newer version of libgtk in Lucid.