Index: trunk/src/change.c
===================================================================
--- trunk/src/change.c	(revision 28778)
+++ trunk/src/change.c	(revision 28779)
@@ -48,6 +48,7 @@
 #include "obj_poly_op.h"
 #include "obj_text_op.h"
 #include "obj_subc_op.h"
+#include "extobj.h"
 
 static const char core_chg_cookie[] = "core: change.c";
 
@@ -838,6 +839,7 @@
 	chg_attr_t *ca = udata;
 	int curr_delete = 0;
 	char *curr_value = NULL, **slot;
+	const char *new_val;
 
 	slot = pcb_attribute_get_ptr(&ca->obj->Attributes, ca->key);
 
@@ -854,9 +856,11 @@
 			slot = pcb_attribute_get_ptr(&ca->obj->Attributes, ca->key);
 		}
 		*slot = ca->value;
+		new_val = ca->value;
 	}
 	else {
 		*slot = NULL;
+		new_val = NULL;
 		pcb_attribute_remove(&ca->obj->Attributes, ca->key);
 	}
 
@@ -864,6 +868,10 @@
 	/* save current state in ca */
 	ca->delete = curr_delete;
 	ca->value = curr_value;
+
+
+	/* side effects */
+	pcb_extobj_chg_attr(ca->obj, ca->key, new_val);
 	return 0;
 }
 
Index: trunk/src/extobj.h
===================================================================
--- trunk/src/extobj.h	(revision 28778)
+++ trunk/src/extobj.h	(revision 28779)
@@ -48,6 +48,7 @@
 	void (*edit_geo)(pcb_subc_t *subc, pcb_any_obj_t *edit_obj); /* called after the geometry of the edit-object changed */
 	void (*float_pre)(pcb_subc_t *subc, pcb_any_obj_t *floater); /* called before an extobj floater is edited in any way - must not free() the floater */
 	void (*float_geo)(pcb_subc_t *subc, pcb_any_obj_t *floater); /* called after the geometry of an extobj floater is changed - must not free() the floater */
+	void (*chg_attr)(pcb_subc_t *subc, const char *key, const char *value); /* called after an attribute changed; value == NULL means attribute is deleted */
 
 	/* dynamic data - filled in by core */
 	int idx;
@@ -177,4 +178,23 @@
 	}
 }
 
+PCB_INLINE void pcb_extobj_chg_attr(pcb_any_obj_t *obj, const char *key, const char *value)
+{
+	pcb_subc_t *subc;
+	pcb_extobj_t *eo;
+
+	if (obj->type == PCB_OBJ_SUBC)
+		subc = (pcb_subc_t *)obj;
+	else
+		subc = pcb_extobj_get_subcobj_by_attr(obj);
+
+	if (subc == NULL)
+		return;
+
+	eo = pcb_extobj_get(subc);
+
+	if ((eo != NULL) && (eo->chg_attr != NULL))
+		eo->chg_attr(subc, key, value);
+}
+
 #endif