Adjust to KToolBarPopupAction API change in KF6
The menu() is no longer to be used, instead, the popupMenu() is.
Undo/Redo buttons on the toolbar have a menu again when built against KF6.
The menu() is no longer to be used, instead, the popupMenu() is.
Undo/Redo buttons on the toolbar have a menu again when built against KF6.