Hi! I have the same problem on Jessie. A workaround is to use https://github.com/PCMan/gtk3-nocsd with libgtk3 3.18.2 (from sid).
(Would be awesome to get that one packaged. :-) Or even more awesome to get this as part of Debian's libgtk3, making the apps just respond to GTK_CSD=0, though that's probably a pipe dream...) -- Petr Baudis If you have good ideas, good data and fast computers, you can do almost anything. -- Geoffrey Hinton