Virtualbox - how to leave scaled mode?

I’m caught in a track: somehow I switched the virtual box window of boot2docker resp. the docker engine to scaled mode and cannot find the button to switch back into unscaled mode (where a toolbar was available), I don’t sse any toolbar anymor in this scaled mode.


Found it: HOST+C was the Key-combination. Though HOST+POS1 didn’t give me the toolbar back.