# self指的是窗口
self.setWindowFlags(Qt.WindowCloseButtonHint)
实例：
class DialogWindows(QtWidgets.QDialog):
def __init__(self, parent=None):
super(DialogWindows, self).__init__(parent)
self.setupUi()
def setupUi(self):
self.setObjectName("Dialog")
self.setFixedSize(369, 128)
self.setWindowFlags(Qt.WindowCloseButtonHint)
