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 1a62fc520..e408a1756 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/util/MutableTreeModel.java
@@ -278,6 +278,14 @@ public class MutableTreeModel<T> extends AbstractTreeModel {
         add(parent, children);
     }
 
+    public void sendContentsChangedEventFor(T object) {
+        Node<T> node = find(object);
+        T parent = getParent(object);
+        Node<T> parentNode = find(parent);
+        int position = parentNode.getIndexOf(node);
+        fireEvent(parent, position, position, TreeDataEvent.CONTENTS_CHANGED);
+    }
+
     public void add(T parent, int position, Collection<? extends T> children) {
         add(find(parent), position, wrap(children));
     }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/tree/EntitiesTree.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/tree/EntitiesTree.java
index 7aee35022..26aa7badb 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/tree/EntitiesTree.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/tree/EntitiesTree.java
@@ -147,6 +147,11 @@ public abstract class EntitiesTree<T extends ITreeNode<T>> {
         ITreeParentNode<T> container = turnIntoContainerIfNeeded(destinationNode);
         container.add(position, elementToAdd.getThis());
         addToTree(container, position, elementToAdd);
+        if (!tree.isRoot(container.getThis())) {
+            // the destination node might have data that depends on its
+            // children, so it should be redrawn
+            tree.sendContentsChangedEventFor(container.getThis());
+        }
         added(destinationNode, elementToAdd, container);
     }
 
@@ -204,6 +209,9 @@ public abstract class EntitiesTree<T extends ITreeNode<T>> {
         T destination = tree.getParent(parent);
         move(nodeToUnindent, destination, getChildren(destination).indexOf(
                 parent) + 1);
+        if (!tree.isRoot(parent)) {
+            tree.sendContentsChangedEventFor(parent);
+        }
     }
 
     private class WithPosition {