Process Button Clicks

OnAction property of the Button object assigns VBA procedure to the button object.
When you press button, xlCompiler calls this routine.
With .AddButton
.Image = "Calendar"
.ImageDisabled = "CalendarDisabled"
.OnAction = "ShowRegPaymentCalendar"
.Tooltip = "Payments Calendar"
End With
Sub ShowRegPaymentCalendar()
' do somtehing
End Sub
OnAction property is used by all ribbon controls.
When selection in the Combobox is changed - routine defined by OnAction button is called.