Mmm, I could make the track move forward using a global variable that another fsm would control..
Playnext Playprevious events could also trigger that..
I can also see the user using the slider to "test" the timelines back and forth (with the pro/cons it adds). But it needs some more work (backward transition navigation, new events, more actions per state, new time slider modes, time keeper in the runtime dll)...
It definitively looks feasible after dirty coding it, I'll give it a shot this week. Very good idea