rearrange notes over bar lines
When notes are inserted or deleted, currently musescore adjusts the values of the adjacent notes so that the number of beats is kept correct. On deletion it just inserts rests instead.
Musescore should have a mode where instead the length of the other notes is untouched. To keep the number of beats correct, the notes are shifted into the next bar on insert or pulled from the next bar on delete.
This mode would be very convenient when transcribing. You could enter the melody first and add the rhythm later.