From Xojo Documentation
If True, an instance of the window can be instantiated implicitly. Set ImplicitInstance in the Properties pane in the IDE.
For example, an implicit instance is instantiated by referring to one of its properties or by calling its Show method. That is, a statement such as:
will instantiate the window.
If ImplicitInstance is False, statements such as:
and references to any window or control properties will produce an error.