A computer-implemented method and system for designing shapes for a software module. Drawing software modules typically provide master shapes that are used as templates in creating drawings. The function of master shapes is generally controlled by behaviors. The invention improves upon existing approaches to designing master shapes by providing a uniform procedure for creating master shapes. The present invention supports the creation of a uniform set of behaviors that are stored independently of the master shapes. The stored behaviors are the preferred methods for controlling the functions of the master shapes. Individual stored behaviors can be selected and used to create the characteristics of a master shape. Using a uniform set of stored behaviors that are implemented in a preferred manner facilitates the management and maintenance of the behaviors and the master shapes they control.