Notes on Interface Controls

Animation vs. "next" button: See Saraiya & Shaffer, 2004 in bibliography

Problem: If you use a "next" button to move through states, and there are distinct phases, then the user might hit the "next" button repeatedly and run through the end of the current phase. Solution: Separate "start" and "next" buttons. At start of a phase, "start" is live and "next" is disabled. Hitting "start" enables "next" (and disables "start"). At the end of the phase, disable "next" and enable "start". Nuisance: Resolves the overshoot problem, but the user must notice and switch buttons.