2 files changed, 29 insertions, 2 deletions
diff --git a/src/com/itmill/toolkit/ui/AbstractComponent.java b/src/com/itmill/toolkit/ui/AbstractComponent.java
index 73afcb6aa8..3508266d91 100644
--- a/src/com/itmill/toolkit/ui/AbstractComponent.java
+++ b/src/com/itmill/toolkit/ui/AbstractComponent.java
@@ -450,15 +450,18 @@ public abstract class AbstractComponent implements Component, MethodEventSource
      */
     public void setParent(Component parent) {
 
-        // If the parent is not changed, dont do nothing
+        // If the parent is not changed, don't do anything
         if (parent == this.parent) {
             return;
         }
 
+        if (parent != null && this.parent != null) {
+            throw new IllegalStateException("Component already has a parent.");
+        }
+
         // Send detach event if the component have been connected to a window
         if (getApplication() != null) {
             detach();
-            this.parent = null;
         }
 
         // Connect to new parent
diff --git a/src/com/itmill/toolkit/ui/AbstractComponentContainer.java b/src/com/itmill/toolkit/ui/AbstractComponentContainer.java
index 5251e99438..d0169535b7 100644
--- a/src/com/itmill/toolkit/ui/AbstractComponentContainer.java
+++ b/src/com/itmill/toolkit/ui/AbstractComponentContainer.java
@@ -169,6 +169,30 @@ public abstract class AbstractComponentContainer extends AbstractComponent
      * @see com.itmill.toolkit.ui.ComponentContainer#addComponent(Component)
      */
     public void addComponent(Component c) {
+        if (c instanceof ComponentContainer) {
+            // Make sure we're not adding the component inside it's own content
+            for (Component parent = this; parent != null; parent = parent
+                    .getParent()) {
+                if (parent == c) {
+                    throw new IllegalArgumentException(
+                            "Component cannot be added inside it's own content");
+                }
+            }
+        }
+
+        if (c.getParent() != null) {
+            // If the component already has a parent, try to remove it
+            try {
+                ComponentContainer oldParent = (ComponentContainer) c
+                        .getParent();
+                oldParent.removeComponent(c);
+            } catch (Exception e) {
+                throw new IllegalStateException(
+                        "Component could be removed from it's old parent.");
+            }
+
+        }
+
         c.setParent(this);
         fireComponentAttachEvent(c);
     }