Better ways to edit duration?

I know that in PRV I can select a group of notes and then change their duration en masse by dragging the left-right arrow on the right side of a selected note. However, this tool seems pretty limited, as all it really can do is change the durations in a purely linear fashion. Is it possible to edit duration on a percentage basis, the way I can with the Velocity dialog? ?Even more useful would be to automatically adjust the durations in the selected passage so that every note takes up the entire duration before the next note. "Fully legato" so to speak (and not more than that, it could also shorten notes whose duration extends past the start of the next note). I find myself doing this manually note by note pretty often. Kind of tedious.