I cannot delete a callback function from my app using the procedure
described by the MathWorks Support Team dated 27 March 2019:
"To delete these functions, navigate to the Code View in App Designer. Then, right click on the callback in the 'Code Browser' pane, under 'Callbacks'.
Right click on the callback, then select 'Delete'."
When I right click on the callback, nothing happens. I cannot get a "Delete" to select.