the last argument to drawback is server of bit flges defined in WINUSER.H.the flags indicate that the text should be displaed as a single line centerd horizontaly & vertically wihin in the  rectngle specified by the fourt arguments.this function call thus causes the string "Hello,window 98 !"to be displayed centered in client area.
WM_DESTROY MESSAGE
                 The WM_DESTROY message is another important message of destroying a window based on command from the user.The message is a re3sult of user clicking on the close button or selecting close from the program's system menu.
              HELLOWIN responds to the WM_DESTROY message by calling in a standard way.
              PostQuitMessage(0);
          This function inserts WM_QUIT message in the programs message queue.GetMessage queue returns nonzero for any message other than WM_QUIT that it retrives from the message queue. When GetMessage retrives a WM_QUIT message , GetMessage returns (0). This causes WinMain to drop outof the message loop.The program then executes the following statement:
                return msg.WParam:
    The WParam field of the structure is the value passed to the PostQuitMessage
function(generally 0). The return statement exits form the WinMain and terminates the program.