f the user right clicks at any Excel cell then the context menu pops up. The
Excel fires the "before right click" event before it displays the menu. The
property OnSheetBeforeRightClick provides facilities for trapping such event.
The signature() method reveals that the event handler is expected to accept
two arguments and return a boolean value. If the returned value is true then
the event would be canceled and the menu would not be displayed.
We insert the event handler as shown below.
Consequently, the context menu no longer pops up and the ControlShell receives
new output every time the user right clicks on a cell.