Piano Roll/Song Editor Marker

It would be nice if LMMS has this "Marker" feature as shown below

**NOTE**: The graphic representation is just a mockup made in photoshop


As a musician, when it comes to music composition most of us put a marker as a personal notes in our musical score/sheet. Most of the time I used another 3rd party tools just to copy paste and mark some notes.

Another use case is that it can be useful to align (like sticky line, so notes easy to snaps) some notes manually, when zoomed out to 25-50% aligning some notes can be really hard (notice the dotted border in the mockup) This feature can be ignored completely if the devs thinks it's a little bit out of context

Thanks for this great piece of a software..

The issue does not identify any files, tests, or entry points. First inspect the piano roll/song editor implementation and existing editing workflows, then define the marker behavior and scope with maintainers before considering implementation.

Written by the indexing model from the issue text.