enabled means the objects inside the form can received mouse events
quick way to disable all objects within a form, hiding a form does not
disabled the objects within it.

non-visible forms and contained objects are not rendered, but the objects
still received mouse events, assuming they are enabled.

when routing mouse events to objects the last form added is checked first.
so if two forms overlap, are both enabled and both have overlapping
objects then the form added first will not received mouse events for its
overlapping objects.