I got the following signature from
the E appendix of  Adam Nathan's
".NET and COM...Interoperability Guide".

   ---------------------------------------------------------
   [DllImport("user32.dll")]
   private static extern IntPtr SetWindowsHookEx
   (
     int idHook,
     HookDelegate lpfn,
     IntPtr hMod,
     uint dwThreadId
   );

  ------------------------------------------------------------

For the most part Nathan's book is over my head.

But I did get it from it not to get too worried
over the superficial differences in the signature
for this that I've seen, in different tutorials on the net.

However, Nathan's generic "HookDelegate"
has to be replaced with something specific.

And I want to hook both, the keyboard,
and the mouse (-via a single declaration
of SetWindowsHookEx().)

So I need a delegate signature that
works for both the keyboard and
the mouse.

Whereas the delegates for these
that I've seen are pretty obviously
incompatible:

 --------------------------------------------
 delegate int KeyboardDelegate
 (
   int code,
   int wparam,
   int lparam
 );

 delegate int MouseDelegate
 (
   int code,
   int wparam,
   ref MOUSEHOOKSTRUCTEX lparam
 );

(MOUSEHOOKSTRUCTEX
being the appropriately defined
structure. )
 ---------------------------------------------

( Replacing "ref MOUSEHOOKSTRUCTEX"
with "int" and then trying to cast "lparam"
to "MOUSEHOOKSTRUCTEX"
-- doesn't work.  )

So, anyway, thank you, anyone,
who understands what I'm asking.

(I'm quite new to all this.
So please forgive me if it's a FAQ
or anything like that.)

~Greg.