typeIControl = interface;   //IControl的Forward声明IWindow = interface['0000-00000-00-00-0000-000']function GetContor(index: integer):IControl;//如果没有IControl的Forward声明,GetControl函数返回IControl类型就是非法的;end;IControl = interface    //IControl的实际声明['0000-00000-00-00-0000-002']function GetWindow:IWindow;end;