Metarnouse is a demonstrational interface for graphical editing tasks within a drawing program. The user specifies a procedure by performing an example execution trace and creating graphical tools where necessary to help make constraints explicit. The system generalizes the user's action sequence, identifying key features of individual steps and disregarding coincidental events. It creates a program with loops and conditional branches as appropriate and predicts upcoming actions, thereby reducing the tedium of repetitive and precise graphical editing. It uses default reasoning about graphical constraints to make initial generalizations and enables the user to correct these hypotheses either by rejecting its predictions or by editing iconic descriptors it displays after each action.