A user interface (UI) may be used in specifying spatial relationships between graphical elements in a graphics environment with drawing or graphical element manipulating functions. The UI interacts with the operating system through an application shell. A document engine, a graphics engine, and a constraint...http://www.google.com/patents/US5437008?utm_source=gb-gplus-sharePatent US5437008 - Method of establishing constraints and links in a distribution frame between graphical elements and resolving the constaints
