code: def _load_gui_setting(self, key, d=None):
          
          # Whether we should pop the value from the dictionary when we set it.
          pop_value = False
          
          # If d is None, assume we're using the lazy load settings.
          if d == None: 
              d = self._lazy_load
              pop_value = True
          
          # If we have a databox, take the header dictionary
          if not type(d) == dict: d = d.headers
          
          # only do this if the key exists
          if key in d:
              
              try:
                  # Try to set the value
                  eval(key).set_value(d[key])
  
                  # If this fails, perhaps the element does not yet exist
                  # For example, TabArea may not have all the tabs created
                  # and cannot set the active tab until later.
                  # If it's here, it worked, so pop if necessary
                  if pop_value: d.pop(key)
             
              except: 
                  print("ERROR: Could not load gui setting "+repr(key))
docs: Safely reads the header setting and sets the appropriate control
          value. 
          
          Parameters
          ----------
          key
              Key string of the format 'self.controlname'.
          d = None
              Databox instance or dictionary, presumably containing the aforementioned
              key. If d=None, pops the value from self._lazy_load.