Have the "Alt" key focus the appbar's ellipsis button when in mobile mode + let tabbing focus both the toolbar and menubar when in desktop mode and fix focusing the appbar drawer in phone mode + appbar drawer size bugs that need to be fixed by replacing. #399

Tab switching isn't that good right now but it needs to be better. Maybe not using a Drawer item will make it possible to do both this and to better implement the appbar button labels and allow the expanded height to be different if desired.

Actually for now it's just switched to opening it with Alt+M because I couldn't figure out the focus thing but I still want to allow using Alt for focusing because it'll be more needed when menubars and desktop layouts are a thing.

I think what I meant by "appbar drawer size bugs" is the thing where the appbar drawer has to be a certain height or else it overlaps the appbar or there's a space between them and it looks bad either way.

Working on hopefully fixing the appbar drawer size bugs in #563.