Comment 25 for bug 1251059

My locale is en_GB so there should be very little difference to en_US. I tried en_US nonetheless and the result is the same.

I tried various DPI settings but they all made no difference. I've never used KDE.

The Mozilla bug is ancient so I'd be surprised if the code isn't vastly different since then.

I'm amazed nobody else seems to have the issue. I haven't changed anything from the default install other than screen resolution, which also doesn't make a difference.

Given the shape of the window I suspect it is something other than locale/text that is the issue. I wonder if it is related to libgtk2.0. The original bug against Gnome 2, and now against MATE, both rely on libgtk2, but Thunderbird now relies on libgtk3. However: that's all a guess and I would expect other apps to be affected. I tried Firefox but they appear to have done away with dialog windows in favour of web pages.