編寫程式碼

from PyQt5 import QtWidgets
from MainForm import Ui_MainForm
from Children import Ui_Form

from PyQt5.QtWidgets import QFileDialog

class MainForm(QtWidgets.QMainWindow,Ui_MainForm):
    def __init__(self):
        super(MainForm,self).__init__()
        self.setupUi(self)

        self.child=ChildrenForm()                          #self.child = children()生成子視窗例項self.child


        self.fileOpen.triggered.connect(self.openMsg)      #選單的點選事件是triggered
        self.fileClose.triggered.connect(self.close)
        self.actionTst.triggered.connect(self.childShow)   #點選actionTst,子視窗就會顯示在主視窗的MaingridLayout中

    def childShow(self):
        self.MaingridLayout.addWidget(self.child)          #新增子視窗
        self.child.show()


    def openMsg(self):
        file,ok=QFileDialog.getOpenFileName(self,"開啟","C:/","All Files (*);;Text Files (*.txt)")
        self.statusbar.showMessage(file)                   #在狀態列顯示檔案地址

class ChildrenForm(QtWidgets.QWidget,Ui_Form):
    def __init__(self):
        super(ChildrenForm,self).__init__()
        self.setupUi(self)

if __name__=="__main__":
    import sys

    app=QtWidgets.QApplication(sys.argv)
    myshow=MainForm()
    myshow.show()
    sys.exit(app.exec_())