Enhancement : Hot-keys (key-shortcuts) for piano-rolls Scale and Chord tools

Mostly because these dropdwns 'disapear' on a std screen, it would be nice if there was key-shortcuts for them. Now the piano-roll need to be moved to the left in order to get to the buttons, then back again. tedious.
(propl not an issue for those with wide-screen 16:4. Not all got that)

Start by locating the piano-roll Scale and Chord tools and their dropdown controls. Determine suitable keyboard shortcuts and how they should work when the controls are off-screen, then verify the behavior on a standard-width display.

Written by the indexing model from the issue text.