WM_WINDOWPOSCHANGED - Syntax

If this message has any of the values of the fl parameter of the SWP structure set, with the exception of the SWP_NOADJUST and SWP_NOREDRAW values, it is sent to the window procedure of the window whose position is changed.

This message is also sent if the return value from the WM_ADJUSTWINDOWPOS is not NULL.

param1
     PSWP   pswp        /*  SWP structures. */

param2
     ULONG  flAwp       /*  Adjust window position status indicators. */