title: Changing the UI of a tab by clicking on a button from another tab
body: <p>I have been creating an application which consists of two tabs. To understand more easily what I want, in Tab1 there is a Start button and by clicking on that I want a table to be added in tab2. There are already some widgets in Tab1 and Tab2 which should be left unchanged. The table should be added to a GroupBox.</p>
  
  <pre><code>import sys
  
  from PyQt5 import *
  from PyQt5.QtGui import *
  from PyQt5.QtCore import *
  from PyQt5.QtWidgets import *
  
  
  class App(QMainWindow):
      def __init__(self):
          super().__init__()
          self.title = 'Application'
          self.setWindowTitle(self.title)
  
          self.tab_widget = MyTabWidget(self)
          self.setCentralWidget(self.tab_widget)
  
          self.showFullScreen()
  
  class MyTabWidget(QWidget):
      def __init__(self, parent):
          super(QWidget, self).__init__(parent)
          self.layout = QVBoxLayout(self)
  
          #Initialize tab screen
          self.tabs = QTabWidget()
          self.one_tab = TabOne()
          self.two_tab = TabTwo()
          self.tabs.resize(300,200)
  
          #Add tabs
          self.tabs.addTab(self.map_tab,QIcon("./icons and images/tab_map.png"), ('Tab1'))
          self.tabs.addTab(self.address_tab,QIcon("./icons and images/tab_addresses.png"), ('Addresses'))
  
  
          #Add tabs to widget
          self.layout.addWidget(self.tabs)
          self.setLayout(self.layout)
  
  class TabOne(QWidget):
      def __init__(self):
          super().__init__()
  
          self.startButton()
  
      #Push button at the center
      def startButton(self):
          button = QPushButton("Start", self)
          button.move(655, 415)
          button.clicked.connect(self.main)
  
          self.show()
  
      def main():
          #Wants to add A table in Tab2
  
  class TabTwo(QWidget):
      def __init__(self):
          super().__init__()
          #Want to add a table after clicking the start button
  
  if __name__ == '__main__':
      app = QApplication(sys.argv)
      ex = App()
      sys.exit(app.exec_())
  </code></pre>
  
  <p>I will add a Table with the help of a JSON file.</p>