Comment 27 for bug 805136

dragging with alt dosent work if your default window manager is some sort of compositing one (well you can drag it but it snaps back if you go over the screen boundry)

rather than try to make the window smaller by removing content making boxes smaller etc surly the best solution is just to have a scroll bar on the prefs boxes that will automatically cater for any size screen. my samsung N140 would then work properly with thunderbird..

also it must be noted that this isnt a problem solely with Thunderbird.... evolution has the same bug :-( https://bugs.launchpad.net/ubuntu/+source/evolution/+bug/23810