In some of the games for the original ipod firmware you can actually control things by 'tapping' the buttons on the ipod, i.e. not actually pressing them down. This means that the play/ffwd/rewind buttons still do what they are supposed to do even while you are in the middle of the game. This got me to thinking that the same thing could be implemented in rockbox, possibly, so for all the menu's, plugins and viewers you use button taps, leaving play/rewind/ffwd always dedicated to playback. You could even make it so the scroll wheel is a dedicated volume control. In theory you are adding twelve more buttons - the four directions and options of single tap, double tap and hold.
I had a quick look to see if someone had had the idea before but couldn't see anything.
I also had a look at the source code and though I could possibly make a plugin as a sort of test but then realised button 'tapping' probably isn't exposed by the API so concluded that it is completely beyond my capabilities.