I learned the principles of user interaction design from Bill. At the time way back in the mid 1980’s the whole notion of metaphors and icons were so new but Bill had a way of patiently explaining his thougts and point of view in a way that us young designers at HP (at a that time) could understand and visualize. Ever since I always remembered the simple principles he had taught us in creating compelling yet understandable user experiences. He was always welcoming and had time to say hi and have a chat at conferences and design events. One of my all time design hero and mentor. I will miss his guidance and wisdom.