Hi, > Any thoughts will be greatly appreciated, Take a look at the MDI and SDI MFC Samples which are shipped with the VTK source code. It should answer your questions. greets Ingo --- Dr.-Ing. Ingo H. de Boer Polytec GmbH Polytec-Platz 1-7, 76337 Waldbronn, Germany phone: ++49 7243 604 106 fax : ++49 7243 604 255