A window receives messages when it changes size or position. Before a change is made, the system might send a WM_ADJUSTWINDOWPOS message to allow the window procedure to make final adjustments to the window's size and position. This message includes a pointer to an SWP structure that contains the requested width, height, and position. If the window procedure adjusts these values in the structure, the system uses the adjusted values to redraw the window. The WM_ADJUSTWINDOWPOS message is not sent if the change is a result of a call to the WinSetWindowPos function with the SWP_NOADJUST constant specified.

After a change has been made to a window, the system sends a WM_SIZE message to specify the new size of the window. If the window has the class style CS_MOVENOTIFY, the system also sends a WM_MOVE message, which includes the new position for the window. The system sends a WM_SHOW message if the visibility of the window has changed.