SetWindowLong with other app's windows

[Razzle]

I want to set some kind of a hook to another app's window to capture all WM messages, so I tried SetWindowLong but it didn't work.
I called it with the window's handle but it always returned zero...

[V(ery) Basic]

You can't do this in VB alone. You need to put a SetWindowsHookEx in a C++ DLL. A VB DLL won't do, because it is ... <ahem> ... just different.

You can hook all mouse and keyboard movements/presses in VB, but not capture all WM messages.

To find more about SetWindowsHookEx, I have kindly provided a link here (http://msdn.microsoft.com/library/psdk/winbase/hooks_7vaw.htm)