diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/DefaultFundamentalProperties.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/DefaultFundamentalProperties.java
index 5fef0a10b..e40018978 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/DefaultFundamentalProperties.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/DefaultFundamentalProperties.java
@@ -77,8 +77,9 @@ public class DefaultFundamentalProperties implements ITaskFundamentalProperties
         return beginDate;
     }
 
-    public void setBeginDate(Date beginDate) {
+    public long setBeginDate(Date beginDate) {
         this.beginDate = beginDate;
+        return lengthMilliseconds;
     }
 
     public long getLengthMilliseconds() {
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/ITaskFundamentalProperties.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/ITaskFundamentalProperties.java
index 787c2d398..5cb7f365f 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/ITaskFundamentalProperties.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/ITaskFundamentalProperties.java
@@ -32,7 +32,12 @@ public interface ITaskFundamentalProperties {
 
     public void setName(String name);
 
-    public void setBeginDate(Date beginDate);
+    /**
+     * Sets the beginDate. As result of this, the length of the task can change.
+     * So the new value is returned
+     * @return the new length
+     */
+    public long setBeginDate(Date beginDate);
 
     public Date getBeginDate();
 
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
index 3fa3c67fe..d01cd9bf8 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
@@ -97,11 +97,13 @@ public abstract class Task implements ITaskFundamentalProperties {
                 previousValue, name);
     }
 
-    public void setBeginDate(Date beginDate) {
+    public long setBeginDate(Date beginDate) {
         Date previousValue = fundamentalProperties.getBeginDate();
-        fundamentalProperties.setBeginDate(beginDate);
+        long oldLength = fundamentalProperties.getLengthMilliseconds();
         fundamentalPropertiesListeners.firePropertyChange("beginDate",
                 previousValue, fundamentalProperties.getBeginDate());
+        fireLengthMilliseconds(oldLength);
+        return fundamentalProperties.getLengthMilliseconds();
     }
 
     public Date getBeginDate() {
@@ -111,6 +113,10 @@ public abstract class Task implements ITaskFundamentalProperties {
     public void setLengthMilliseconds(long lengthMilliseconds) {
         long previousValue = fundamentalProperties.getLengthMilliseconds();
         fundamentalProperties.setLengthMilliseconds(lengthMilliseconds);
+        fireLengthMilliseconds(previousValue);
+    }
+
+    private void fireLengthMilliseconds(long previousValue) {
         fundamentalPropertiesListeners.firePropertyChange("lengthMilliseconds",
                 previousValue, fundamentalProperties.getLengthMilliseconds());
     }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
index 924982ae3..221254645 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
@@ -118,9 +118,10 @@ public class TaskElementAdapter implements ITaskElementAdapter {
         }
 
         @Override
-        public void setBeginDate(Date beginDate) {
+        public long setBeginDate(Date beginDate) {
             taskElement.setStartDate(beginDate);
             updateEndDate();
+            return lengthMilliseconds;
         }
 
         @Override