content: sub main()
      screen= CreateObject("roSGScreen")
      m.port= CreateObject("roMessagePort")
      screen.setMessagePort(m.port)
      scene= screen.CreateScene("MainScene")
      screen.show()
      while(true)
          msg= wait(0, m.port)
          msgType= type(msg)
  
          if msgType= "roSGScreen"
              if msg.isScreenClosed() then return 
          end if
      end while
  end sub 