For anyone on Linux having the ALT-TAB problem with fullscreen (crashing on ALT-TAB), do the following:

Switch DA2 to Window mode

In your Desktop, go to Settings | Keyboard | Shortcuts | Windows

Define a keyboard shortcut for "Toggle Fullscreen State", for example Windows+Pos1

This will allow you to use a borderless window which is NOT fullscreen mode. ALT-TAB is possible then.

I have posted this here so people struggling with the same problem can find it.