Extension class which allows grouping of document objects Create and add an object with given type and name to the group Add an object to the group. Returns all objects that have been added. Adds multiple objects to the group. Expects a list and returns all objects that have been added. Sets the objects of the group. Expects a list and returns all objects that are now in the group. Remove an object from the group and returns all objects that have been removed. Remove multiple objects from the group. Expects a list and returns all objects that have been removed. Remove all child objects from the group and document Return the object with the given name hasObject(obj, recursive=false) Checks if the group has a given object @param obj the object to check for. @param recursive if true check also if the obj is child of some sub group (default is false).