Hi Olaf,

> Is it possible to DECLARE functions of the VFP runtime, like you can DECLARE Win API calls?

No. You can only declare exported functions. VFP only exports 9 functions, all of which deal with COM.

> Then their technique should work in DOS too, shouldn't it?

Nope, because in DOS the API interface is completely different. DOS calls base on raising an interrupt with a register having the function code. Also, API calls are only relevant when you make calls across a module. Intra-module calls are resolved by the linker and therefore hard coded. There's no generic technology that lets you hook into a procedure in a DLL unless you have the compiled object code and are able to re-link a product.