Please add a USE-flag to enable the SDL-userinterface of the vice-emulator. Although the menu does not support mouse-usage and is a bit hidden since you have to press F12 to open the menu), it offers MUCH more useability. It's fullscreenmode just works in contrast to some bugs/flaws of the current standard Gentoo-build, you can configure the joystick-controller in a much more pleasing way and even add emulator-shortcut-configurations for joystick-buttons.
IMHO this UI should even be made the standard-interface due to all the additional options. But even if not, then a message should be output after installation to inform the user, that he might want to switch to it.
Additionally an install-message reading that you can open the menu by pressing F12 would be good.
To enable the UI the sourcecode has to be configured/compiled with the "--enable-sdlui" being enabled. I would provide such an ebuild myself, but i barely managed to get it somehow done with dirty hacks for personal usage and don't think that offering it for public makes any sense.
Beside the above I would also welcome a current-svn-snapshot-ebuild (something like "vice-99999.ebuild)
Please do not conflate several issues in one bug. If want a live ebuild added to the tree, report a separate enhancement bug.
sdl is available in vice-2.4.16-r1