* make a shared "main menu dialog", based on the SCUMM one
** accessible via the same hotkey in all engines
help optional** enhance the current dialog by displaying the engine name at the top, maybe also "ScummVM 0.x.y"
* Highlight the "default" button in dialogs (e.g. the classic MacOS way, drawing a fat border around it; or by using different coloring; or a combination). This falls under "usability", too.