   Fullscreen --> window mode
  When we want to create a fullscreen mode using directX 9.0. We need to create a window that has a style called WS_POPUP. In many game, they allow the user that click ALT+ENTER for convert the window mode and fullscreen mode. In my problem, I want to know how to do it? Because when we create a window with WS_POPUP style in the WinMain, can we change the WS_STYLE? Or we need to create another window for supporting the window mode? How can do it?Pls help me and thx your help ^_^ 
  Why not look at the SDK samples?  They all do that. ;  I don''t know the SDK''s example can do it, because I don''t try it in the example, but now I know it, anyway thx for you first ^_^ 