I am looking for information on subclasing a window in an application not written by me. I can get the HWND of the window, but any attempts to manipulate the window in any way fail. I can SetWindowText and send messages such as WM_CLOSE easily, they work fine. But when I try to use SetWindowLong with GWL_WNDPROC to replace the window proc with my own, it fails.

I have tried creating a CWnd and calling SubclassWindow, it returns true, and yet no calls are made top PreTranslateMessage or DefWindowProc. Any help? Thanks.

JL