Here’s a small sample that shows this in action:
https://blog.xojo.com/wp-content/uploads/2018/12/WindowSuper.zip
@Jason Parsley Nice example: the super of Window1 is NOT Window but MyWindowSuper and the super of MyWindowSuper is Window. So Window1 inherits from MyWindowSuper and MyWindowSuper inherits from Window. Is this example you add functionality to the normal Window ‘class’. Am I correct?
Yes. The example shows you how to insert your own custom class into the inheritance chain of the Window layouts you design in the IDE. And by doing that you can insert methods, events, constants etc - just not UI. And you can do this sort of thing with a lot of classes.