Small suggestion for the system track: Make both the trash and the select buttons always visible on the screen when selecting.
I often click a measure in the system track, scroll forward to choose the measure ending the selection, and then scroll all the way back to hit the delete button. (The same issue with the select button, except it disappears when scrolling back.)
I would love it if the delete/select buttons were visible on the right and left hand of the screen rather than the left and right side of the selection.