That has been discussed, it was not generally agreed upon.
Can you formulate a really strong usecase, where that feature would be epic?
Make sure to search to see if your idea has been posted before! Check our issue tracker as well, just to make sure you are not posting a duplicate: https://github.com/LMMS/lmms/issues
You're creating in piano roll and have multiple section, 17 or so.
Is that something you do when you compose?