Temporarily mute one staff of keyboard system for playback
On the Mastering Musescore forum, Marc Sabella, in response to a user's question about how to mute just one staff of a keyboard part, suggested: "If it's just an occasional "mute the RH" type of thing, you can select all on that staff, then use the Properties panel to disable 'Play'".
But I'd like to see a better way to do this: something less invasive, more direct, and more visible -- like individual mute buttons in the mixer, let's say, for each staff. On a piece I'm working on currently, I leave myself the option in different mixes to play the bass line with an electric bass rather than the left hand of the keyboard. I'd rather have an immediately visible indication that I'm muting the keyboard's left hand than have that fact hidden in individual properties of the notes.
And what happens if I already have some notes set not to play in the staff I want to mute? I sometimes do this, for example, in order to have note or musical line alternatives as I'm working on a piece, or for different circumstances. (I'll give the alternative note a small notehead in addition to setting it not to play.) If I were then to select all notes in the staff and set them not to play, all the information about which notes were supposed to sound, and which not, would be lost.