docs: def validateSignal(self, policy=None):
          """
          Validates that this view is part of the group that was emitting
          the signal.  Views that are not in any viewing group will accept
          all signals.
          
          :param      policy | <XView.SignalPolicy> || None
          
          :return     <bool>
          """
          # validate whether or not to process a signal
          if policy is None:
              policy = self.signalPolicy()
          
          group_check   = XView.getGlobal('emitGroup') == self.viewingGroup()
          current_check = self.isCurrent()
          
          # always delegate signals if they are not set to block,
          # or if the method is called directly (not from a signal)
          if not self.sender() or policy & XView.SignalPolicy.NeverBlock:
              return True
          
          # block delegation of the signal if the view is not initialized
          elif policy & XView.SignalPolicy.BlockIfNotInitialized and \
               not self.isInitialized():
              return False
          
          # block delegation if the view is not visible
          elif policy & XView.SignalPolicy.BlockIfNotVisible and \
              not self._visibleState:
              return False
          
          # block delegation if the view is not part of a group
          elif self.viewingGroup() and \
               policy & XView.SignalPolicy.BlockIfNotInGroup:
              return group_check
          
          # look for only currency releated connections
          elif policy & XView.SignalPolicy.BlockIfNotCurrent:
              return current_check
          
          else:
              return True