Venkat V.S.S. Sastry, PhD is lecturer in scientific computing at RMCS, Cranfield University, Shrivenham, United Kingdom where he teaches commercial and academic courses on programming using C, Tcl/Tk and other software packages. Venkat Sastry played a significant role in developing a knowledge based front end to NAG Software Library in early 90's, and is currently the principal architect of developing this work further using Tcl/Tk. He is the co-author of the Tcl/Tk Cookbook. Lakshmi Sastry is principal applications designer and developer, Advanced Interactive Systems Group, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom. She has extensively used and reviewed commercial and public domain 2D graphical user interface development tools and has authored several reviews for the benefit of UK academic community She is a co-author of the Tcl/Tk Cookbook, and is a member of IEEE.