Stretch-A-Sketch is a pen-based drawing program that combines recognition of hand-drawn glyphs with constraint based maintenance of spatial relations. The recognition program identifies hand drawn glyphs, spatial relations between them, and higher-level configurations, such as graph and tree diagrams and floorplan bubble diagrams. Stretch-A-Sketch then maintains the essential relations in these configurations as the user edits the diagram.

Electronic Cocktail Napkin, Smart Objects