My initial idea about modifying track.C was wrong, but even simpler mod (attached) makes selection by setting in/out points and attaching plugin from menu work...

in sense your plugin legth now can be set by setting i/o points not by just mouse selection or making few cuts with 'x' blade and then selecting block.. 

Phyllis, Andrea - can you give this patch a lot of testing? I mean with many tracks (armed/disarmed), many plugins, shared plugins, gang modes, etc...?