There is a menubutton for that menu already. And if you can move the mouse to view the tooltip, you can move the mouse to click the menubutton without pressing F10.
Tooltips are so-called because they're intended for toolbars, where space is too scarce to provide proper labels. If there was ever any program where this is *not* a problem, it's gdm. Half a dozen elements in the entire screen. -- "Username" field contains nonsensical tooltip https://launchpad.net/bugs/70786 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
