need two-step tie-untie functionality for Shift+=
When all notes in a selection have ties, Shift+= should remove those ties. Presently it has no effect in such cases.
Shift+= already results in all selected notes getting ties when a mixed selection is made. This should not be changed; rather, the above requested functionality should be added. i.e. It should then be possible to remove all ties from a mixed selection by typing the command twice: type it once and all notes have ties; type it again and all of these ties are removed.
Presently it is possible to delete all ties from a range selection by right-clicking a selected tie, selecting all similar elements, and deleting. However, this involves fine mousing which poses challenges for some users. A keyboard-based solution is needed.
A recent discussion: