Question

Does anyone know the WM_MESSAGE that is sent when a window has been maximized (either by the maximize button being pressed in the title bar, or by double clicking the title bar?)

Is there a windows message for the maximize button being pressed?

Win32/C++, thanks.

Answer 1

You get the WM_SIZE message with the value SIZE_MAXIMIZED in wParam

Edit

The @jamesdlin comment bellow called my atention to WM_WINDOWPOSCHANGED documentation, which states (emphasis mine):

Remarks
By default, the DefWindowProc function sends the WM_SIZE and WM_MOVE messages to the window. The WM_SIZE and WM_MOVE messages are not sent if an application handles the WM_WINDOWPOSCHANGED message without calling DefWindowProc. It is more efficient to perform any move or size change processing during the WM_WINDOWPOSCHANGED message without calling DefWindowProc.

Thanks james!