# -*- coding: utf-8 -*-
import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
class DialogDemo(QMainWindow):
  def __init__(self, parent=None):
    super(DialogDemo, self).__init__(parent)    
    self.setWindowTitle("Dialog 示例")
    self.resize(350,300)
    self.btn = QPushButton( self)
    self.btn.setText("弹出对话框")  
    self.btn.move(50,50)
    # 点击按钮弹出一个新的对话框   
    self.btn.clicked.connect(self.showdialog)  
  def showdialog(self ):
    dialog = QDialog()
    btn = QPushButton("ok", dialog)
    btn.move(50,50)
    dialog.setWindowTitle("Dialog")
    dialog.setWindowModality(Qt.ApplicationModal)
    dialog.exec_()
if __name__ == '__main__':
  app = QApplication(sys.argv)
  demo = DialogDemo()
  demo.show()
  sys.exit(app.exec_())