Given Window Handle, listen for on Handle Rect Change event

Question

I have a handle (HWND) to a window and I want to listen for bounding rectangle changes. I could check the GetWindowRect(HWND hWnd, LPRECT lpRect); every n milliseconds, but that seems really wasteful.

Is there a Windows message that I can listen for?

The window handle is not to a window I own.

Answer 1

I think you can do this if you use SetWindowsHookEx to install a hook function, and then listen for WM_SIZE messages.