Keep double clicking on the QTableWidget, the QItemDelegate can't create QWidget any more

when I create a QTableWidget ,add create a custom class inherited from QItemDelegate， I override the createEditor,setEditorData and setModelData function. then, I create a other custom class A inherited from QWidget,In class A ,I create a QPushButton,when I click the QPushButton,it will close the A object. in the createEditor function,I create a QPushButton and return it.when I Keep double clicking in the QTableWidget cell,the cell is disabled and can't create A object any more.