Hello all,
I just install MagiMirror on a new RPI5 and I get the same problem : Alt key doesn’t give me the menu.
I have compared electron.js from an old installation that works fine with the one I just install on my RPI5 and I remark the line “electronOptionsDefaults.autoHideMenuBar = true;” is missing in the new version. I add this line in the new version, similar place in the code list, and now the Alt command works like the old version : I get the menu.
So it is solved for me, until the next update of electron.js file…

If it can help you…

EricD