Handles the drag move event.
        
        :param      event | <QDragEvent>

def dragMoveEvent( self, event ):
        """
        Handles the drag move event.
        
        :param      event | <QDragEvent>
        """
        tags = nativestring(event.mimeData().text())
        
        if ( event.source() == self ):
            event.acceptProposedAction()
        elif ( tags ):
            event.acceptProposedAction()
        else:
            super(XMultiTagEdit, self).dragMoveEvent(event)