diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
index f79afe6b9..dfd7ef828 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
@@ -21,13 +21,10 @@ public class DependencyComponent extends XulElement implements AfterCompose {
 
     private TaskComponent destination;
 
-    private DependencyType type;
-
     private FunctionalityExposedForExtensions<?> context;
 
     public DependencyComponent(FunctionalityExposedForExtensions<?> context,
             TaskComponent source, TaskComponent destination) {
-        this.type = DependencyType.END_START;
         this.context = context;
         if (source == null)
             throw new IllegalArgumentException("source cannot be null");
@@ -105,11 +102,7 @@ public class DependencyComponent extends XulElement implements AfterCompose {
     }
 
     public DependencyType getDependencyType() {
-        return this.type;
-    }
-
-    public void setType(DependencyType type) {
-        this.type = type;
+        return getDependency().getType();
     }
 
     public boolean hasSameSourceAndDestination(Dependency dependency) {
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java
index 91fd52d82..4b0d70b91 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java
@@ -155,8 +155,8 @@ public class DependencyList extends XulElement implements AfterCompose {
                         @Override
                         public void onEvent(final DependencyComponent choosen,
                                 Event event) {
-                            choosen.setType(DependencyType.END_START);
-                            choosen.invalidate();
+                            context.changeType(choosen.getDependency(),
+                                    DependencyType.END_START);
                         }
                     });
 
@@ -165,8 +165,8 @@ public class DependencyList extends XulElement implements AfterCompose {
                         @Override
                         public void onEvent(final DependencyComponent choosen,
                                 Event event) {
-                            choosen.setType(DependencyType.START_START);
-                            choosen.invalidate();
+                            context.changeType(choosen.getDependency(),
+                                    DependencyType.START_START);
                         }
                     });
 
@@ -175,8 +175,8 @@ public class DependencyList extends XulElement implements AfterCompose {
                         @Override
                         public void onEvent(final DependencyComponent choosen,
                                 Event event) {
-                            choosen.setType(DependencyType.END_END);
-                            choosen.invalidate();
+                            context.changeType(choosen.getDependency(),
+                                    DependencyType.END_END);
                         }
                     });
 
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
index a56c3b9ad..b2e77c174 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
@@ -13,6 +13,7 @@ import org.zkoss.ganttz.adapters.IDomainAndBeansMapper;
 import org.zkoss.ganttz.adapters.IStructureNavigator;
 import org.zkoss.ganttz.adapters.PlannerConfiguration;
 import org.zkoss.ganttz.data.Dependency;
+import org.zkoss.ganttz.data.DependencyType;
 import org.zkoss.ganttz.data.GanttDiagramGraph;
 import org.zkoss.ganttz.data.ITaskFundamentalProperties;
 import org.zkoss.ganttz.data.Position;
@@ -270,4 +271,9 @@ public class FunctionalityExposedForExtensions<T> implements IContext<T> {
         getDependencyList().remove(dependency);
     }
 
+    public void changeType(Dependency dependency, DependencyType type) {
+        removeDependency(dependency);
+        addDependency(dependency.createWithType(type));
+    }
+
 }
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/Dependency.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/Dependency.java
index 3cbee242c..b1790c11a 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/Dependency.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/Dependency.java
@@ -110,8 +110,8 @@ public class Dependency {
         return visible;
     }
 
-    public void setType(DependencyType type) {
-        this.type = type;
+    public Dependency createWithType(DependencyType type) {
+        return new Dependency(source, destination, type, visible);
     }
 
 }
\ No newline at end of file