docs: def keyPressEvent( self, event ):
          """
          Overloads the base QGraphicsScene method to handle individual \
          key overrides.
                      
          :param      event       <QKeyPressEvent>
          """
          # otherwise, eat all other key press events until the 
          # view mode is released
          if ( self.inViewMode() ):
              event.accept()
          
          # when the user presses the space bar, put
          # the scene into view editing mode
          elif ( event.key() == Qt.Key_Space ):
              self.setViewMode(True)
              event.accept()
          
          # cancel the connection if escape is pressed
          elif ( event.key() == Qt.Key_Escape ):
              self.finishConnection(False)
              event.accept()
          
          # otherwise, run the standard key press event
          else:
              super(XNodeScene, self).keyPressEvent(event)