1. A method of enabling incremental development of a graphical editor, comprising: executing an editor engine component to create the graphical editor, further comprising: processing, by the editor engine component, a visual model structural file to programmatically determine details specified, in the visual model structural file, for a visual model to be supported by the graphical editor, wherein: the visual model structural file adheres to a specified visual meta-model and identifies an externally-stored visual model descriptor file; the details specified in the visual model structural file comprise: a plurality of visual elements of the visual model; at least one visual relationship among at least two of the visual elements of the visual model; for each of the visual elements, a reference to an element descriptor specified for that visual element in the externally-stored visual model descriptor file; and for each of the at least one visual relationship, a reference to a relationship descriptor specified for that visual relationship in the externally-stored visual model descriptor file and an identification of each of the at least two visual elements; and a domain model for a particular domain is loosely coupled to the visual model structural file by specifying, in the visual model structural file, a location of an externally-stored file where a descriptor for the domain model for the particular domain is stored and specifying, in the visual model structural file for each of the plurality of visual elements of the visual model, a reference to an object from the domain model that is to be associated with that visual element, such that the visual model structural file supports graphical editing of a different domain by replacing the specified location; and processing, by the editor engine component, the identified visual model descriptor file to configure behavior of the visual model in the graphical editor, wherein: the identified visual model descriptor file specifies constraints on the visual model and adheres to a specified visual descriptor meta-model; the specified constraints define bounds for allowable operations of the behavior and comprise at least one composition behavior of at least one of the visual elements of the visual model, at least one permitted behavior of at least one of the visual elements, and at least one prohibited behavior of at least one of the visual elements; and the visual model descriptor file specifies, for each of a plurality of types of domain objects, a reference to an edit part to be used for editing domain objects of that type in the graphical editor and a reference to a shape object to be used for representing domain objects of that type in the graphical editor; evaluating the configured behavior of the visual model using the created graphical editor; determining, as a result of the evaluating, at least one additional requirement for the visual model; revising the visual model descriptor file to specify at least one of the at least one additional requirement; and re-executing the editor engine component to re-create the graphical editor using the revised visual model descriptor file, thereby re-configuring the behavior of the visual model in the graphical editor.