If InitSprite() = 0
    MessageRequester("Error", "Can't open screen & sprite enviroment!", 0)
    End
  EndIf
  
  If OpenWindow(0, 0, 0, 220, 160, "A screen in a window...", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
    ButtonGadget(0, 170, 135, 45, 20, "Quit")

    If OpenWindowedScreen(WindowID(0), 0, 0, 160, 160, 0, 0, 0)
      CreateSprite(0, 20, 20)
      If StartDrawing(SpriteOutput(0))
        Box(0, 0, 20, 20, RGB(255, 0, 155))
        Box(5, 5, 10, 10, RGB(155, 0, 255))
        StopDrawing()
      EndIf
    Else
      MessageRequester("Error", "Can't open windowed screen!", 0)
      End
    EndIf
  EndIf
  
  direction = 2
  Repeat
    ; It's very important to process all the events remaining in the queue at each frame
    ;
    Repeat
      Event = WindowEvent()
      
      Select Event 
        Case #PB_Event_Gadget
          If EventGadget() = 0
            End
          EndIf
        
        Case #PB_Event_CloseWindow
          End 
      EndSelect
    Until Event = 0
  
    FlipBuffers() 
    ClearScreen(RGB(0, 0, 0))
    DisplaySprite(0, x, x)
    x + direction
    If x > 140 : direction = -2 : EndIf
    If x < 0   : direction =  2 : EndIf
    Delay(1)
  ForEver