Hi all, I've installed GTK+ 3.14 from Sid in my Debian Testing VM. Guess what. Those weird headers in sub-windows are gone. Now these windows can be resized almost normally (almost - because it sometimes works only on the 2nd try, but maybe it's just my theme which hasn't been updated since GTK+ 3.10).
I found out that Gnome guys might have really fixed it, like they've promised [1]. I've tested this in nm-connection-editor and Synaptic's package properties window. I'm using MATE. Please check this in your DEs/WMs as well and see whether this bug can be considered fixed. [1] http://blogs.gnome.org/mclasen/2014/07/28/a-talk-in-9-images/
