This is really annoying. It has been fixed upstream at https://bugzilla.mozilla.org/show_bug.cgi?id=352096 Can we get that patch in rawhide, caillon ?
The patch doesn't apply, and uses newer APIs than were available in 1.5.0.7. I just attached a backported patch to the upstream bug, though.
Fix is in firefox-1.5.0.7-5.fc6