Element templates can be used with Desktop Modeler version 1.0+; they are currently available in BPMN diagrams only.
Element templates are a way to extend Desktop Modeler with domain-specific diagram elements, such as service and user tasks.
If applicable, element templates can be assigned to a diagram element via the properties panel. Once applied, element templates configure the diagram element with pre-defined values for BPMN properties, input/output mappings, and extension properties.
As seen in the Mail Task example above, Modeler allows properties of custom elements to be edited, too.