AbstractComponent.setParent(parent) cannot be called if component already has parent, unless the new parent is null (unsetting parent).

AbstractComponentContainer.addComponent(component) removes the component from it's previous ComponentContainer if needed (moves component), or throws if the component can't be removed.

Fixes #1137

All components that contain other components should implement ComponentContainer for this to be perfect (e.g CustomComponent, Table)

svn changeset:3698/svn branch:trunk

1 files changed, 5 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