content: function init()
      print "in PhotoAppMainScene init()"
  
      m.top.backgroundColor = "0x111111"
      m.top.backgroundUri=""
      m.loadingIndicator = m.top.FindNode("loadingIndicator")
  
      InitScreenStack()
      ShowGroupScreen()
  end function
  
  function OnKeyEvent(key as String, press as Boolean) as Boolean
      result = false
      if press
          if key = "back"
              numberOfScreens = m.screenStack.Count()
              if numberOfScreens > 1
                  CloseScreen(invalid)
                  result = true
              end if
          end if
      end if
      return result
  end function