content: function showScreen(screenName as string)
      if screenName = invalid return invalid
      ' Hide current top scene
      if m.screenStack.count() > 0
          m.screenStack.peek().visible = false
      end if
  
      ' Create new scene
      newScene = CreateObject("roSGNode", screenName)
      m.screenContainer.appendChild(newScene)
      m.screenStack.push(newScene)
      return newScene
  end function
  
  sub closeScreen()
      if m.screenStack.count() > 1
          topScene = m.screenStack.pop()
          m.screenContainer.removeChild(topScene)
  
          prevScene = m.screenStack.peek()
          if prevScene <> invalid
              prevScene.visible = true
          end if
      else
          print "Can't go back. This is the root scene."
      end if
  end sub
  