If https://forum.parallels.com/threads/change-behaviour-of-clicking-the-menu-bar-icon.339815/ doesn't get implemented:
Keep focus with Toolbox, consider adding the ability to press Command-Z to undo the last command (a history stack might be overkill). Command-Y or Command-Shift-Z could be added for redo.
Keep focus with Toolbox, consider adding the ability to press Command-Z to undo the last command (a history stack might be overkill). Command-Y or Command-Shift-Z could be added for redo.