Currently we have popover for quite some things, that’s great – but when I need to reach for menu items (say, changing noteheads, splitting beams, creating stemlets) or property options (change the look of triplets, silencing notes, switching strings), in most cases I still need to do quite some mouse clicks. Sure, assigning key command is a way to go, but those features are not used in a day to day basis so it would be a question of who to assign and how complicated should it be.
So, maybe having a popover would solve such problem. Let’s have “Shift + . (dot)”, or maybe “Shift + U” for “menU”, which would bring up a popover, that I can type something like “beam” and it would have commands like “split beam” and “join together” show up in the drop down, and I can select what I want and do it that way. Same for properties, it can share the same popover, or maybe another one (Say, “Shift + K” for “looK”), and I can type things like “type” on a slur and have all the slur type options available in the drop down, along with a “default”. Or if I know what I want I can type “type flat”.
Such kind of thing is more or less expected for programming IDEs, but I’d say composing/notating is equally keyboard intensive so anything that can reduce mouse click is preferred, when it can be done.