SendMessage (whatever window) WM_MOVE 0 (position) doesn't work

Why doesn't it work?
Maybe it needs a redraw or something?

From MSDN:

The WM_MOVE message is sent after a window has been moved.

This message is a notification message. It doesn't make the window move, it only notifies it after it has been moved. Call the MoveWindow API function using the System plug-in to move a window.

The following Wiki pages contain an example of moving a window: