Intercepts the Qt key released event to look for built-in overrides.
        
        :param      event       <QKeyReleaseEvent>

def keyReleaseEvent( self, event ):
        """
        Intercepts the Qt key released event to look for built-in overrides.
        
        :param      event       <QKeyReleaseEvent>
        """
        # when the user releases the space bar, remove
        # the scene view edit override
        if ( event.key() == Qt.Key_Space ):
            self.setViewMode(False)
            event.accept()
        
        # otherwise, eat all other key press events until the 
        # view mode is released
        elif ( self.inViewMode() ):
            event.accept()
        
        # otherwise, handle the event like normal
        else:
            super(XNodeScene, self).keyPressEvent(event)