@ Luciano,

thanks for the link.

during the many hours of searching the web for examples I had already found it.

eventhough this example was not very clear to me it has helped to solve the problem.

@Mel,

I have never asked for "ready to run" code,
just some pointers to get started.

however, the problem is solved, and you have pointed out that there is no reason for me to feel bad with not sharing the solution.