Support base class event handler definition
Description:
Currently for C++ generated classes, if you specify that the class will be derived, then all event handlers are declared virtual and call event.Skip();. If you specify that you will not be creating a derived class, then event handlers are not declared virtual, and they have no default body. What you can't do is mix and match -- i.e., you can't add your own base class default handler if you state you plan on deriving from the class. Now that you can add your own code to a file after the generated code, it could sometimes be useful to create a base class handler that does more than just call event.Skip();. This would make it possible to override it if needed, even calling the base implementation as part of the override.
Ideally, this would be on a per-event basis rather than a per-form basis. Otherwise, you are forced to provide a body in the base class for every event. A better solution would be to add it to the C++ event handler. If use_derived_class is checked, then in the function block, a checkbox for Ommit call to event.Skip() in header would make it possible for the dev to create their own definition of the event handler.