Eighth-rests (16th, 32nds, etc) are positioned too high. The bottom of the rest should come into contact with the staff line below it, and there should be a gap between the top of the rest and the staff line above it.

Also, these types of rests can currently be placed on every diatonic step. However, in music notation they are only allowed to occur on every other diatonic step (excluding when they occur off of the
staff). It would be useful if invalid vertical placements are excluded when using the up/down arrow is used to position the rests.