RNA:

* Added support for using pointers + collections as operator properties,
  but with the restriction that they must point to other type derived from
  ID property groups. The "add" function for these properties will allocate
  a new ID property group and point to that.
* Added support for arrays with type IDP_GROUP in ID properties.
* Fix bug getting/setting float array values.

Example code for collections, note the "OperatorMousePath" type is defined
in rna_wm.c and has a float[2] property named "loc".


Defining the operator property:

prop= RNA_def_property(ot->srna, "path", PROP_COLLECTION, PROP_NONE);
RNA_def_property_struct_runtime(prop, &RNA_OperatorMousePath);


Adding values:

PointerRNA itemptr;
float loc[2] = {1, 1},

RNA_collection_add(op->ptr, "path", &itemptr);
RNA_float_set_array(&itemptr, "loc", loc);


Iterating:

RNA_BEGIN(op->ptr, itemptr, "path") {
	float loc[2];

	RNA_float_get_array(&itemptr, "loc", loc);
	printf("Location: %f %f\n", loc[0], loc[1]);
}
RNA_END;

source/blender/blenloader/intern/writefile.c

@@ -390,6 +390,14 @@ static void IDP_WriteArray(IDProperty *prop, void *wd)
 	/*REMEMBER to set totalen to len in the linking code!!*/
 	if (prop->data.pointer) {
 		writedata(wd, DATA, MEM_allocN_len(prop->data.pointer), prop->data.pointer);
+
+		if(prop->type == IDP_GROUP) {
+			IDProperty **array= prop->data.pointer;
+			int a;
+
+			for(a=0; a<prop->len; a++)
+				IDP_WriteProperty(array[a], wd);
+		}
 	}
 }