I'm surprised this question has not come up before...
It did, and IIRC(?) it was skidracer who mentioned the panel solution that I half-remembered (whad'ya think - that I'm some kinda genius? ;) ).
The docs indicate that the cell sizes must be constant, so I think you're right about that. And there still seems to be some weirdness about the icon used by a toggle button (that was to have been fixed/documented a while back). Note how the right-most floppy icon turns into a light bulb when clicked (in Windows, anyway).