diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/Planner.java b/ganttzk/src/main/java/org/zkoss/ganttz/Planner.java
index 2588fce4a..59f95b05e 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/Planner.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/Planner.java
@@ -262,6 +262,10 @@ public class Planner extends HtmlMacroComponent  {
                 configuration.isDependenciesConstraintsHavePriority());
         FunctionalityExposedForExtensions<T> newContext = new FunctionalityExposedForExtensions<T>(
                 this, configuration, diagramGraph);
+        diagramGraph.addPreChangeListeners(configuration
+                .getPreChangeListeners());
+        diagramGraph.addPostChangeListeners(configuration
+                .getPostChangeListeners());
         this.contextualizedGlobalCommands = contextualize(newContext,
                 configuration.getGlobalCommands());
         this.commandsOnTasksContextualized = contextualize(newContext,
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java b/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
index 7de0c65a9..4eb8e684d 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/adapters/PlannerConfiguration.java
@@ -29,6 +29,7 @@ import java.util.Map;
 
 import org.apache.commons.lang.Validate;
 import org.zkoss.ganttz.Planner;
+import org.zkoss.ganttz.data.GanttDiagramGraph.IGraphChangeListener;
 import org.zkoss.ganttz.data.constraint.Constraint;
 import org.zkoss.ganttz.data.constraint.DateConstraint;
 import org.zkoss.ganttz.extensions.ICommand;
@@ -150,6 +151,10 @@ public class PlannerConfiguration<T> implements IDisabilityConfiguration {
 
     private boolean expandPlanningViewCharts;
 
+    private final List<IGraphChangeListener> preGraphChangeListeners = new ArrayList<IGraphChangeListener>();
+
+    private final List<IGraphChangeListener> postGraphChangeListeners = new ArrayList<IGraphChangeListener>();
+
     public PlannerConfiguration(IAdapterToTaskFundamentalProperties<T> adapter,
             IStructureNavigator<T> navigator, List<? extends T> data) {
         this.adapter = adapter;
@@ -380,4 +385,24 @@ public class PlannerConfiguration<T> implements IDisabilityConfiguration {
         return expandPlanningViewCharts;
     }
 
+    public void addPreGraphChangeListener(
+            IGraphChangeListener preGraphChangeListener) {
+        Validate.notNull(preGraphChangeListener);
+        preGraphChangeListeners.add(preGraphChangeListener);
+    }
+
+    public void addPostGraphChangeListener(
+            IGraphChangeListener postGraphChangeListener) {
+        Validate.notNull(postGraphChangeListener);
+        postGraphChangeListeners.add(postGraphChangeListener);
+    }
+
+    public List<IGraphChangeListener> getPreChangeListeners() {
+        return Collections.unmodifiableList(preGraphChangeListeners);
+    }
+
+    public List<IGraphChangeListener> getPostChangeListeners() {
+        return Collections.unmodifiableList(postGraphChangeListeners);
+    }
+
 }
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
index 2705d10ae..427f0b0ae 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDiagramGraph.java
@@ -123,6 +123,20 @@ public class GanttDiagramGraph implements ICriticalPathCalculable<Task> {
         postGraphChangeListeners.remove(postGraphChangeListener);
     }
 
+    public void addPreChangeListeners(
+            Collection<? extends IGraphChangeListener> preChangeListeners) {
+        for (IGraphChangeListener each : preChangeListeners) {
+            addPreGraphChangeListener(each);
+        }
+    }
+
+    public void addPostChangeListeners(
+            Collection<? extends IGraphChangeListener> postChangeListeners) {
+        for (IGraphChangeListener each : postChangeListeners) {
+            addPostGraphChangeListener(each);
+        }
+    }
+
     public GanttDiagramGraph(List<Constraint<Date>> globalStartConstraints,
             List<Constraint<Date>> globalEndConstraints,
             boolean dependenciesConstraintsHavePriority) {
@@ -1158,7 +1172,6 @@ public class GanttDiagramGraph implements ICriticalPathCalculable<Task> {
         }
         return result;
     }
-
 }
 
 interface IReentranceCases {