--- a/engine/core/model/structures/instance.cpp	Sun Mar 15 18:59:49 2009 +0000
+++ b/engine/core/model/structures/instance.cpp	Sun Mar 15 22:20:20 2009 +0000
@@ -170,6 +170,17 @@
 	}
 
 	Instance::~Instance() {
+                std::vector<InstanceDeleteListener *>::iterator itor;
+                for(itor = m_deletelisteners.begin();
+                    itor != m_deletelisteners.end();
+                    ++itor) {
+                        (*itor)->onInstanceDeleted(this);
+                }
+                if(m_activity &&
+                   m_activity->m_actioninfo &&
+                   m_activity->m_actioninfo->m_leader) {
+                        m_activity->m_actioninfo->m_leader->removeDeleteListener(this);
+                }
 		delete m_activity;
 		delete m_facinglocation;
 		delete m_visual;
@@ -271,6 +282,7 @@
 		m_activity->m_actioninfo->m_target = new Location(leader->getLocationRef());
 		m_activity->m_actioninfo->m_speed = speed;
 		m_activity->m_actioninfo->m_leader = leader;
+                leader->addDeleteListener(this);
 		setFacingLocation(*m_activity->m_actioninfo->m_target);
 		FL_DBG(_log, LMsg("starting action ") <<  action_name << " from" << m_location << " to " << *m_activity->m_actioninfo->m_target << " with speed " << speed);
 	}
@@ -510,4 +522,25 @@
 		}
 		return TimeManager::instance()->getTime();
 	}
+        void Instance::addDeleteListener(InstanceDeleteListener *listener) const {
+                m_deletelisteners.push_back(listener);
+        }
+        void Instance::removeDeleteListener(InstanceDeleteListener *listener) const {
+                std::vector<InstanceDeleteListener*>::iterator itor;
+                itor = std::find(m_deletelisteners.begin(),
+                                 m_deletelisteners.end(),
+                                 listener);
+                if(itor != m_deletelisteners.end()) {
+                        m_deletelisteners.erase(itor);
+                } else {
+                        FL_WARN(_log, "Cannot remove unknown listener");
+                }
+        }
+        void Instance::onInstanceDeleted(Instance* instance) {
+                if(m_activity && 
+                   m_activity->m_actioninfo && 
+                   m_activity->m_actioninfo->m_leader == instance) {
+                        m_activity->m_actioninfo->m_leader = NULL;
+                }
+        }
 }

--- a/engine/core/model/structures/instance.h	Sun Mar 15 18:59:49 2009 +0000
+++ b/engine/core/model/structures/instance.h	Sun Mar 15 22:20:20 2009 +0000
@@ -70,10 +70,17 @@
 		virtual void onInstanceChanged(Instance* instance, InstanceChangeInfo info) = 0;
 	};
 
+
+	class InstanceDeleteListener {
+	public:
+		virtual ~InstanceDeleteListener() {};
+		virtual void onInstanceDeleted(Instance* instance) =0;
+	};
+
 	/**
 	 *  An Instance is an "instantiation" of an Object at a Location.
 	 */
-	class Instance : public ResourceClass {
+	class Instance : public ResourceClass, public InstanceDeleteListener {
 	public:
 
 		/** Constructor
@@ -169,6 +176,16 @@
 		 */
 		void removeChangeListener(InstanceChangeListener* listener);
 
+		/** Adds new instance delete listener
+		 * @param listener to add
+		 */
+		void addDeleteListener(InstanceDeleteListener* listener) const;
+
+		/** Removes associated instance delete listener
+		 * @param listener to remove
+		 */
+		void removeDeleteListener(InstanceDeleteListener* listener) const;
+
 		/** Gets the currently active action. This is owned by
 		 *  the instance's object, so don't delete it!
 		 * @return current action, NULL in case there is none
@@ -261,6 +278,10 @@
 		 */
 		inline InstanceChangeInfo getChangeInfo();
 
+		/** callback so other instances we depend on can notify us if they go away 
+		*/
+		void onInstanceDeleted(Instance* instance);
+
 	private:
 		std::string m_id;
 
@@ -312,6 +333,8 @@
 		InstanceActivity* m_activity;
 		// bitmask stating current changes
 		InstanceChangeInfo m_changeinfo;
+		// listeners for deletion of the instance
+		mutable std::vector<InstanceDeleteListener*> m_deletelisteners;
 
 		// object where instantiated from
 		Object* m_object;