Mac: QLineEdit and the Qt Undo Framework does not play well together

On Mac, when using QLineEdit the cmd+z interferes with your the undo command
that is in the menu. This results in that when QLineEdit has focus, and
you do cmd+z it does not undo from the Qt Undo action that is
application menu. When another widget than a QLineEdit has focus you
get the Qt Undo action.

It would be expected that cmd+z would always trigger the Qt Undo action that was in the menu
bar no matter if a QLineEdit has focus.

It would be expected that any command keys always ran the QAction associated with the qaction/menu that has that command key tied to it.
The behaviour of a menu item with a command key menu doing one thing when you click in the menu and another when you use the command key and a particular widget has focus makes the behaviour seem broken.