CONE environment will pass the redraw event to the application which is in foreground. By default exe in symban does not have CONE environment in it, So if your exe have graphics in it than it require redraw events issued by window server. It is required when your application is overlapped by some other application, for example call dialog overlapped your application and then disappear after some time, so your application need invalid rect overlapped by call dialog. Thus we need to implement listener to get redraw event issued by window server.
Article describes basic steps required to implement redraw event listener. This require use of Active Objects, so basic knowledge of Active objects is necessary. Article is useful to both beginners as well as experienced developer.
--kamlesh sangani 12:21, 6 September 2009 (UTC)