displaying several working/looping piano rolls simultaneously

[norayr]

only found such request on forum: https://lmms.io/forum/viewtopic.php?t=26334

Enhancement Summary

currently only one piano roll can be shown and can play/loop simultaneously.
i suggest allowing as many piano rolls as the use needs to loop and being edited simultaneously.

Justification

a) lmms has no live performance functionality and adding it would be too hard. however it already has the piano roll which loops. by having several looping piano rolls it would be possible to use lmms for live performances.

b) that would help in the process of composing - to have several piano rolls looping, and think of what would fit good with those several layers.

Mockup