feature request: lock rhythm button

Too often I inadvertently change the rhythm of some note (often losing some nearby notes in the process) because I forget to switch to note edit mode before switching to a different duration value. "Undo" works quite well, but only if I'm immediately aware that I modified something by accident. Sometimes the change happens without me being aware about it and then it takes a long time before I find out (and at that time, undo is no longer an option). For me, it would be nice to have a "lock rhythm" button, so that when it's activated, you can still select/copy/paste ranges but not modify any rhythm.