New Piano Roll Window

[krispy]

Not sure if anyone will read this, but I was thinking that instead of putting the piano roll in the bottom "sample" window, it would make more sense to have it as a third tab on the main "arrangement" / "session" window, i.e., the main window could show arrangement, session, or piano roll. then there would be much more real-estate for the piano roll, and the bottom sample window wouldn't have to stretched to some awkward looking size.