best idiom for dealing with existing controls

[theodox]

in a couple of places the current code uses this idiom to work with existing controls:

 @classmethod
 def from_existing(cls, widget):
      try:
      _cache = cls.CMD
      def fake_CMD(*args, **kwargs):
            return widget
      cls.CMD = fake_CMD
      return cls(widget, widget)
      finally:
           cls.CMD = _cache

This seems to work, but I'm nervous about it. It won't be thread safe (not a major concern - the gui stuff is thread hell no matter what) and it will need extra work for things like parsing existing menus with submenus....

[theodox]

I've added this to mGui.core:

   @classmethod
   def wrap(cls, control_name, key=None):

       def _spoof_create(*args, **kwargs):
           return control_name

        try:
            cache_CMD = cls.CMD
            cls.CMD = _spoof_create
            key = key or control_name
           return cls(key, control_name)
        finally:
            cls.CMD = cache_CMD

Which makes the idiom part of the base mGui,control