I cannot switch to fullscreen in Debian 12. For some reason, Alt-Enter makes a window of the same size as the windowed DOSBox in the edge of the screen. The contents of the new window seems to be scaled correctly (it is a part of the windowed DOSBox contents). Moreover, DOSBox is hanging. Luckily, you can Alt-Enter back and close the window (using the 'x', keyboard is hanging).

It is completely new, DOSBox worked perfectly until now. I have tried to change to "machine=vgaonly", different options for "output", and starting with fullscreen directly. Nothing helps.

What is it all about?