It actually does work. I did find an issue though.
I went to fullscreen. then closed bsnes with alt-F4.
Now whenever I start bsnes it will start in the top left corner of my screen. The mainmenu controls are out of my reach and there is no way I can move the window elsewhere. Anyone else having this?
edit: Well I can restore the window by deleting my geometry.cfg. Tried exitting with alt f4 a couple of times and it will still put the window out of reach. It allmost feels like its "fake fullscreen". The window seems to be moved to 0,0 the window gets resized to desktop resolution and put in a modal state that goes (most of the times but not allways) over the taskbar but the fullscreen window doesnt seem to have focus. To be able to exit with alt f4 in fullscreen most of the times I have to alt-tab to the bsnes window (eventhough it suggests I'm still there) and only then the window will be able to be closed with alt-f4.