Hi Pieterjan,
Just out of curiosity, you have a stand alone .windows application, and you are accessing the B1 client from it. Why, is there something you can not do through the DI API ? If you need to show the user something in the B1 client, or if you need to prefill some information or something, why not create an addon ?
I ask, because several years ago, a colleague of mine had built a similar solution, which I later discovered was done because he didn't know that he could use certain functionality through the DI API as well.
Regards,
Johan