title: Open second window from main with pyqt5 and qt designer
body: <p>I'm creating an application with two windows using pyqt5 and QtDesigner. A button on the main window "MainWindow.ui" should open a second window from the file "age_entry.ui" but I seem to be missing something. Clicking the button on the first form produces this error":</p>
  
  <blockquote>
    <p>Exception "unhandled TypeError"
    QDialog(parent: QWidget = None, flags: Union[Qt.WindowFlags, Qt.WindowType] = Qt.WindowFlags()): argument 1 has unexpected type 'bool'</p>
  </blockquote>
  
  <p>Here is the code for the main window:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  import sys
  from PyQt5 import uic, QtWidgets
  
  
  Ui_MainWindow, QtBaseClass = uic.loadUiType("MainWindow.ui")
  LandingPageUI, LandingPageBase = uic.loadUiType("age_entry.ui")
  
  class MyApp(QtWidgets.QMainWindow, Ui_MainWindow):
  
      def __init__(self):
          QtWidgets.QMainWindow.__init__(self)
          Ui_MainWindow.__init__(self)
          self.setupUi(self)
  
          def showAgeEntryForm(self):
              self.child_win = AgeEntryForm(self)
              self.child_win.show()             
  
          self.btnOpenAges.clicked.connect(showAgeEntryForm)            
  
  
  class AgeEntryForm(LandingPageBase, LandingPageUI):
      def __init__(self, parent=None):   
          LandingPageBase.__init__(self, parent)
          self.setupUi(self)            
  
  
  
  if __name__ == "__main__":
      app=QtWidgets.QApplication.instance()
      if not app: 
           app = QtWidgets.QApplication(sys.argv)
  
      window = MyApp()
      window.show()
      sys.exit(app.exec_())
  </code></pre>
  
  <p>Thanks in advance! </p>
  
  <p>Here is the MainWindow and age_entry file in code form:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  # Form implementation generated from reading ui file 'MainWindow.ui'
  #
  # Created by: PyQt5 UI code generator 5.7
  #
  # WARNING! All changes made in this file will be lost!
  
  from PyQt5 import QtCore, QtGui, QtWidgets
  
  class Ui_MainWindow(object):
      def setupUi(self, MainWindow):
          MainWindow.setObjectName("MainWindow")
          MainWindow.resize(526, 338)
          self.centralwidget = QtWidgets.QWidget(MainWindow)
          self.centralwidget.setObjectName("centralwidget")
          self.label_9 = QtWidgets.QLabel(self.centralwidget)
          self.label_9.setGeometry(QtCore.QRect(90, 10, 341, 41))
          font = QtGui.QFont()
          font.setPointSize(16)
          font.setBold(True)
          font.setWeight(75)
          self.label_9.setFont(font)
          self.label_9.setObjectName("label_9")
          self.btnOpenAges = QtWidgets.QPushButton(self.centralwidget)
          self.btnOpenAges.setGeometry(QtCore.QRect(130, 90, 181, 61))
          self.btnOpenAges.setObjectName("btnOpenAges")
          MainWindow.setCentralWidget(self.centralwidget)
          self.menubar = QtWidgets.QMenuBar(MainWindow)
          self.menubar.setGeometry(QtCore.QRect(0, 0, 526, 21))
          self.menubar.setObjectName("menubar")
          MainWindow.setMenuBar(self.menubar)
          self.statusbar = QtWidgets.QStatusBar(MainWindow)
          self.statusbar.setObjectName("statusbar")
          MainWindow.setStatusBar(self.statusbar)
  
          self.retranslateUi(MainWindow)
          QtCore.QMetaObject.connectSlotsByName(MainWindow)
  
      def retranslateUi(self, MainWindow):
          _translate = QtCore.QCoreApplication.translate
          MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
          self.label_9.setText(_translate("MainWindow", "Ageing Session Management"))
          self.btnOpenAges.setText(_translate("MainWindow", "Enter Ages"))
  </code></pre>
  
  <p>And the age_entry.ui</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  # Form implementation generated from reading ui file 'age_entry.ui'
  #
  # Created by: PyQt5 UI code generator 5.7
  #
  # WARNING! All changes made in this file will be lost!
  
  from PyQt5 import QtCore, QtGui, QtWidgets
  
  class Ui_Dialog(object):
      def setupUi(self, Dialog):
          Dialog.setObjectName("Dialog")
          Dialog.resize(350, 189)
          self.label_13 = QtWidgets.QLabel(Dialog)
          self.label_13.setGeometry(QtCore.QRect(90, 20, 451, 61))
          font = QtGui.QFont()
          font.setPointSize(14)
          self.label_13.setFont(font)
          self.label_13.setObjectName("label_13")
  
          self.retranslateUi(Dialog)
          QtCore.QMetaObject.connectSlotsByName(Dialog)
  
      def retranslateUi(self, Dialog):
          _translate = QtCore.QCoreApplication.translate
          Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
          self.label_13.setText(_translate("Dialog", "Age Entry Form"))
  </code></pre>