Possibly via right-click on piano keys? Useful for drum clips. Mute/solo specific sounds in the kit. Should be fast and affecting the whole row. (no select all notes, mute-all notes etc... it has to affect the whole row even if you add new notes)
Right-clicking the correct piano key and pressing Alt + M works here. Ctrl+Right-click selects notes on multiple keys if needed. That help? D EDIT: Hmmm... no 'Solo' though...
That ^^ is the ordinary note mute toggle. A fair workaround, but the problem with that method is when you had individual notes of that pitch muted beforehand, these will become unmuted afterwards. It's like item mute vs track mute in main view. One doesn't make the other obsolete.