1. A computer-readable medium having stored thereon a data structure, the data structure comprising: a property storage structure that is configured to store properties associated with a display object; a property object included in the property storage structure, wherein the property object corresponds to a property of the display object; a key that is included in the property object, wherein the key identifies the property object; and a value that is hierarchically included in the property object corresponding to the key, wherein the value designates a type associated with the property object.