Sketching storyboards to illustrate interface behaviors

Current user interface construction tools make it difficult for a user interface designer to illustrate the behavior of an interface. These tools focus on specifying widgets and manipulating details such as colors. They can show what the interface will look like, but make it hard to show what it will do. For these reasons, designers prefer to sketch early interface ideas on paper. We have developed a tool called SILK that allows designers to quickly sketch an interface electronically. Unlike paper sketches, this electronic sketch is interactive. The designer can illustrate behaviors by sketching storyboards, which specify how the screen should change in response to user actions.