Disable mouse drag ability for Measure Rests because they can't be easily laid out while dragging
A very minor but noticeable slightly annoying glitch occurs while dragging Measure Rests:
This occurs because Measure Rests are supposed to be laid out in the center of their measure...but unfortunately it is not easy to lay them out because their x position is dependent on layout of their parent measure. So to make things simple, to avoid this glitch I'm going to disable this ability. I doubt anyone will complain. They may still adjust position of measure rests by using inspector x/y offset or pressing up/down on keyboard.