new_contents: from guizero import App, Box, Text, PushButton, Combo, Slider
  
  def switch_screen(switch_to):
      hide_all()
      switch_to.show()
  
  def hide_all():
      for screen in all_screens:
          screen.hide()
      
  
  app = App("Multi window app", layout="grid")
  
  # Create a blank list to hold all the different screens
  all_screens = []
  
  # Create a box to contain the menu buttons
  menu = Box(app, grid=[0,0], layout="grid")
  menu.tk.width = 900
  menu.bg = "red"
  
  # Option 1 box
  option1 = Box(app, grid=[1,1])
  text1 = Text(option1, text="This is the first page of stuff")
  combo = Combo(option1, options=["Beef", "Chicken", "Fish", "Vegetarian"])
  all_screens.append(option1)
  
  # Option 2 box
  option2 = Box(app, grid=[1,1])
  text2 = Text(option2, text="This is the second page of stuff")
  slider = Slider(option2)
  all_screens.append(option2)
  
  # Add the screens to the menu box
  option1_button = PushButton(menu, text="Option 1", command=switch_screen, args=[option1], grid=[0,0], align="left")
  option2_button = PushButton(menu, text="Option 2", command=switch_screen, args=[option2], grid=[1,0], align="left")
  
  # Hide all screens and then show the first one
  hide_all()
  all_screens[0].show()
  
  app.display()
  
subject: Add multi window example