Overloads the base QGraphicsScene method to handle individual \
        key overrides.
                    
        :param      event       <QKeyPressEvent>

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)