I'm not sure how many current features of Musescore have a toggle operation. One is tremolo, and this can be manipulated very quickly across two instruments - or for example for an instrument like the marimba with a score written out over two staves.
Imagine a section with the top line played tremolo, and the other line played straight. If both lines in the section are selected, then the tremolo is selected, the result is that the tremolo swaps between the instruments or parts.
This is a very quick way of swapping effects over, but tremolo might be unusual in this respect.