text: #!/usr/bin/env python3
  # -*- coding: utf-8 -*-
  
  import sys
  
  from PyQt5 import QtCore, QtWidgets, uic
  from PyQt5.QtCore import pyqtSlot
  
  # import capture tool screen
  from captureTool import CaptureTool
  # import enter tool screen
  from enterTool import EnterTool
  # import select tool screen
  from selectTool import SelectTool
  
  MainWindowUI, MainWindowBase = uic.loadUiType("main.ui")
  
  
  class Ui_MainWindow(MainWindowBase, MainWindowUI):
      def __init__(self, parent: QtWidgets.QWidget = None):
          MainWindowBase.__init__(self, parent=parent)
          self.setupUi(self)
  
          # UI items event connection
          self.captureToolButton.clicked.connect(self.captureToolScreen)
          self.selectToolButton.clicked.connect(self.selectToolScreen)
          self.enterToolButton.clicked.connect(self.enterToolScreen)
  
      @pyqtSlot(name="captureToolButton")
      def captureToolScreen(self):
          # code for capture tool screen here!
          self.captureTool = CaptureTool()
          self.captureTool.show()
  
      @pyqtSlot(name="selectToolScreen")
      def selectToolScreen(self):
          # code for select tool screen here!
          self.selectTool = SelectTool()
          self.selectTool.show()
  
      @pyqtSlot(name="enterToolScreen")
      def enterToolScreen(self):
          # code for enter tool screen here!
  
          self.enterTool = EnterTool()
          self.enterTool.show()
  
      def retranslateUi(self, MainWindow):
          _translate = QtCore.QCoreApplication.translate
          MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
          self.captureToolButton.setText(_translate("MainWindow", "Capture Tool"))
          self.selectToolButton.setText(_translate("MainWindow", "Select Tool"))
          self.enterToolButton.setText(_translate("MainWindow", "Enter Tool"))
  
  
  if __name__ == "__main__":
      app = QtWidgets.QApplication(sys.argv)
      MainWindow = Ui_MainWindow()
      MainWindow.show()
      sys.exit(app.exec_())
  