Free floating / bottom panels
As someone unfamiliar with music instruments, the the new percussion window's ability to preview sounds without placing a note is a feature that would be wonderful if it was not so obtrusive!
Personally, I find in general, using the bottom or free-floating panels is a frustrating experience. On a laptop or monitor, it covers most of the score, so it makes a feature like the percussion panel that are designed to be used simultaneously with note-input feel annoying rather than helpful, especially when turned on by default (see below GIFS for examples). Shortly after installing the new update I disabled the percussion pop-up altogether, which I think is a shame when the tool itself is something I could see myself really benefiting from.
TL;DR: a small feature that would greatly improve user experience IMO would be automatic centering of the selected percussion instrument to the visible section of the screen for bottom panels, or above/below for free-floating panels