diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java b/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java
index e408a1756..b0cdb8198 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java
@@ -386,6 +386,10 @@ public class MutableTreeModel<T> extends AbstractTreeModel {
         return getChildCount(node) > 0;
     }
 
+    public boolean contains(T object) {
+        return find(object) != null;
+    }
+
     public boolean contains(T parent, T child) {
         Node<T> parentNode = find(parent);
         Node<T> childNode = find(child);
diff --git a/ganttzk/src/test/java/org/zkoss/ganttz/util/MutableTreeModelTest.java b/ganttzk/src/test/java/org/zkoss/ganttz/util/MutableTreeModelTest.java
index fd021f4fb..fe375e423 100644
--- a/ganttzk/src/test/java/org/zkoss/ganttz/util/MutableTreeModelTest.java
+++ b/ganttzk/src/test/java/org/zkoss/ganttz/util/MutableTreeModelTest.java
@@ -488,6 +488,18 @@ public class MutableTreeModelTest {
         assertThat(model.getChild(model.getRoot(), 1), equalTo(prueba2));
     }
 
+    @Test
+    public void canBeKnownIfAnEntityIsOnTheTree() {
+        final MutableTreeModel<Prueba> model = MutableTreeModel
+                .create(Prueba.class);
+        Prueba prueba1 = new Prueba();
+        model.addToRoot(prueba1);
+
+        assertTrue(model.contains(prueba1));
+        assertTrue(model.contains(model.getRoot()));
+        assertFalse(model.contains(new Prueba()));
+    }
+
     @Test
     public void treeParentContainsChild() {
         final MutableTreeModel<Prueba> model = MutableTreeModel