The WM_CHILDACTIVATE message is sent to a multiple document interface (MDI) child window when the user clicks the window's title bar or when the window is activated, moved, or sized.
WM_CHILDACTIVATE
This message has no parameters.
If an application processes this message, it should return zero.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Windows Overview, Window Messages, MoveWindow, SetWindowPos