As these popup windows appear only in the GUI and not in the mission I cannot use the ingame screenshot button. Fraps does not work either, it just takes a screenshot from the screen as if these popup windows were not there.
(perhaps this may be linked to the cause of the problem, that these popup windows are somewhat not so much really there).

So I have made a picture with my old cell phone so the quality is really bad.

This is the popup window (FLUGZEUGWAHL translated to Plane selection) where this bug is the second most annoying (the most annoying is when I want to assign a key and I cannot click on the buttons in the popup menue for a specific keybind):



The menue window with the plane pictures in it is what I call a popup window or popup menue. I cannot click on anything within any popup window with my mouse after having played Clod for a while.

NOTA: after having played Clod for a few minutes this bug appears for ALL popup windows in the game (plane selection, exit popup windows from server and from game, keybinding popup menues, ...).

I can usually access the buttons in the popup menues (like ok, yes, cancel) by using TAB and ENTER. But when I am about to change a keybinding and I press TAB to access the OK button it overrides my initial keybinding and thinks I want to assign TAB to this function.

I also cannot access the little plane pictures in the plane selection popup windows by pressing TAB. So in the pictured popup plane selection menue I just can access the filter option and the close button with using TAB.