KDiff3 missing window controls after upgrade to Ubuntu 18

Question

I recently upgrade from Ubuntu 16 to Ubuntu 18.04.4. When I open kdiff3 it only opens into a maximized window with no controls visible (minimize/maximize/close).

If I invoke from Applications menu (or command line without any files specified), the controls are initially visible when the file picker modal is visible, but then disappear when I hit OK or Cancel.

I cannot drag the window by the header. F11 has no effect. Clicking Alt+Space does show a menu, but Resize, Unmaximize, and Move are grayed out.

$ kdiff3 --version
Qt: 4.8.7
KDE Development Platform: 4.14.38
kdiff3: 0.9.98 (64 bit)

Answer 1

Try changing WindowStateMaximised to false by editing config file ~/.config/kdiff3rc.

This helped for me. Seems there is no GUI option for that. Don't know why it was set to true anyway.