Small undocumented "feature" that you might want to use.
Mamewah can display multiple snapshots of each game during the screensaver. I use this on my Daphne emulator since there are so few games. The multiple snaps have to have the same name, just a different extension. Since Mamewah supports several graphic formats, you can have additional snaps using those different formats (e.g. lair.png lair.jpg lair.gif)
It will always display the same snap on your layout (based on its hierarchy I guess), but for screensaver mode, it will use all valid formats.
Rocky