[Accessibility] - Custom key signature creation not accessible

The custom key signature creation dialog is quite inaccessible. The box doesn't accept keyboard operation. Even sighted people feel difficult to place accidentals to right place, since one of them said the staff is too small. If possible, implement a navigation command, up/down arrows to select pitches and NVDA read them, then right click to bring a menu with accidentals, saying sharp and flat, press enter to apply.