Quote Originally Posted by Eric
As suggested, pausing the game would be a user-friendly solution to that. When selecting 'windowed', you usually want to be able to click on other things - if only to move the game window around your desktop
As I supposed, this absolutely doesn't work for my game. Gamecursor is "independend" from Windows mouse cursor. I move the mous ingame using my own calculations. So if I turn the turret with mouse, my ingame cursor points to the place I want to shoot. The Windows cursor is off the game screen in most cases. When firing with mouseclick, the game looses focus.
Shortly said, you can't play it this way.

I think about a solution that pressing ESC (Pause game/Options screen) enables the windows mouse again, because then I use a 2D cursor which I can point to the Windows cursor position. Ingame I have a 3D cursor, using it's own coordinates which doesn't match to windows cursor.

Would this solution be ok for you?