Hi Ehsan,
Since you are using MPI.Net, from my understanding, your question is a MPI.Net question not a MSMPI question. MPI.NET is different from MSMPI.
MPI.Net web site: http://www.osl.iu.edu/research/mpi.net/
Whether MPI.Net can do what you want (GUI application), you may have to consult MPI.Net user group.
thanks,
Liwei