Double hit instead of one hit

see picture below. By hitting “F” one time nothing happens. I have to hit “F” twice to the the result.
Any idea ?
Thanks a lot, Chris

It will run the “windowed” command first, so If you are starting the game in windowed mode, you won’t see any different.

Yes of course, but this not my problem. Everytime I will switch the state I have to hit F twice.
Not only at the beginning of the level.