Intercepting Windows Messages - How?

How do I intercept the Activation of applications in Windows? Would I
need a callback filter function? If so - how do you do it and which
Windows messages would I need to intercept? If not this any ideas would
be greatly appreciated.

Richard D. Williams  Voice +44 (0)161-406-7399 Fax +44 (0)161-406-7410
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