Checks to make sure that the view widget can be properly closed.
        
        :param      event | <QCloseEvent>

def closeEvent(self, event):
        """
        Checks to make sure that the view widget can be properly closed.
        
        :param      event | <QCloseEvent>
        """
        if not self.viewWidget().canClose():
            event.ignore()
        else:
            super(XViewDialog, self).closeEvent(event)