diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
index dfd7ef828..6c4726654 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyComponent.java
@@ -5,6 +5,7 @@ import java.beans.PropertyChangeListener;
 
 import org.zkoss.ganttz.data.Dependency;
 import org.zkoss.ganttz.data.DependencyType;
+import org.zkoss.ganttz.data.GanttDiagramGraph;
 import org.zkoss.ganttz.data.Task;
 import org.zkoss.zk.au.out.AuInvoke;
 import org.zkoss.zk.ui.ext.AfterCompose;
@@ -21,15 +22,17 @@ public class DependencyComponent extends XulElement implements AfterCompose {
 
     private TaskComponent destination;
 
-    private FunctionalityExposedForExtensions<?> context;
+    private DependencyType type;
 
-    public DependencyComponent(FunctionalityExposedForExtensions<?> context,
-            TaskComponent source, TaskComponent destination) {
-        this.context = context;
+    public DependencyComponent(TaskComponent source, TaskComponent destination,
+            DependencyType type) {
+        this.type = type;
         if (source == null)
             throw new IllegalArgumentException("source cannot be null");
         if (destination == null)
             throw new IllegalArgumentException("destination cannot be null");
+        if (type == null)
+            throw new IllegalArgumentException("type must be not null");
         this.source = source;
         this.destination = destination;
     }
@@ -96,13 +99,13 @@ public class DependencyComponent extends XulElement implements AfterCompose {
         return destination;
     }
 
-    public Dependency getDependency() {
-        return context.getDiagramGraph().getDependencyFrom(source.getTask(),
+    public Dependency getDependency(GanttDiagramGraph diagramGraph) {
+        return diagramGraph.getDependencyFrom(source.getTask(),
                 destination.getTask());
     }
 
     public DependencyType getDependencyType() {
-        return getDependency().getType();
+        return type;
     }
 
     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 7c0dc9120..d30547519 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/DependencyList.java
@@ -35,7 +35,7 @@ public class DependencyList extends XulElement implements AfterCompose {
 
         @Override
         public void onEvent(final DependencyComponent choosen, Event event) {
-            context.changeType(choosen.getDependency(), type);
+            context.changeType(dependencyFor(choosen), type);
         }
     }
 
@@ -160,8 +160,8 @@ public class DependencyList extends XulElement implements AfterCompose {
                                 public void onEvent(
                                         final DependencyComponent choosen,
                                         Event event) {
-                                    context.removeDependency(choosen
-                                            .getDependency());
+                                    context
+                                            .removeDependency(dependencyFor(choosen));
                                 }
                             });
             contextMenuBuilder.item("Set End-Start", new ChangeTypeAction(
@@ -229,4 +229,9 @@ public class DependencyList extends XulElement implements AfterCompose {
             }
         }
     }
+
+    private Dependency dependencyFor(
+            final DependencyComponent dependencyComponent) {
+        return dependencyComponent.getDependency(context.getDiagramGraph());
+    }
 }
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java b/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
index 8d34775a4..53658e7bb 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
@@ -75,9 +75,9 @@ public class TaskList extends XulElement implements AfterCompose {
         }
         List<DependencyComponent> result = new ArrayList<DependencyComponent>();
         for (Dependency dependency : dependencies) {
-            result.add(new DependencyComponent(context, taskComponentByTask
+            result.add(new DependencyComponent(taskComponentByTask
                     .get(dependency.getSource()), taskComponentByTask
-                    .get(dependency.getDestination())));
+                    .get(dependency.getDestination()), dependency.getType()));
         }
         return result;
     }