pythonpyqtpyqt5qdialogqmessagebox

Hiding PyQt main window affects behaviour of child dialog


In PyQt5, I'm wondering why hiding a QMainWindow affects the behaviour of child dialogs?

For example, in the code below, if I click "Show dialog" -> "OK", the QMessageBox is displayed then the program terminates. However, if I comment out the self.hide() and self.show() in showChildDialog(), the program returns to showing the child dialog after the QMessageBox is displayed.

Ideally, I would like the program to return to the child dialog after displaying the QMessageBox, but I also want to hide the main window while the child dialog is displayed.

How can I achieve both behaviours simultaneously?

from PyQt5 import QtWidgets


class mainWindow(QtWidgets.QMainWindow):
   def __init__(self, parent=None):
       super(mainWindow, self).__init__(parent)

       self.dialog = childDialog(self)

       self.setWindowTitle('Main Window')

       self.buttonShow = QtWidgets.QPushButton(self)
       self.buttonShow.setText("Show Dialog")
       self.buttonShow.clicked.connect(self.showChildDialog)

   def showChildDialog(self):
       self.hide()                 # works as intended if this commented out...
       self.dialog.exec()
       self.show()                 # and this.


class childDialog(QtWidgets.QDialog):
   def __init__(self, parent=None):
       super(childDialog, self).__init__(parent)

       self.buttonOk = QtWidgets.QPushButton(self)
       self.buttonOk.setText("OK")
       self.buttonOk.clicked.connect(self.ok_clicked)

       self.buttonHide = QtWidgets.QPushButton(self)
       self.buttonHide.setText("Close")
       self.buttonHide.clicked.connect(self.hide_clicked)

       self.layout = QtWidgets.QVBoxLayout(self)
       self.layout.addWidget(self.buttonOk)
       self.layout.addWidget(self.buttonHide)

   def hide_clicked(self):
       self.accept()

   def ok_clicked(self):
       # do somehting here that causes an error
       dialog = QtWidgets.QMessageBox(text='an error occurred')
       dialog.exec()


if __name__ == "__main__":
   import sys

   app = QtWidgets.QApplication(sys.argv)
   app.setApplicationName('myWindow')

   main = mainWindow()
   main.show()

   sys.exit(app.exec_())

Solution

  • if you change this line:

    self.dialog = childDialog(self)
    

    to this line:

    self.dialog = childDialog()
    

    it works properly.