Need Explainations....

[thinh]

Can anybody explains to me how to use the two functions below?
Declare Function CallWindowProc Lib "user32.dll" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Declare Function DefWindowProc Lib "user32.dll" Alias "DefWindowProcA" (ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Thanks alotttttttt.

CallWindowProc
http://www.vbapi.com/ref/c/callwindowproc.html

DefWindowProc
http://www.vbapi.com/ref/d/defwindowproc.html