src/share/tools/IdealGraphVisualizer/Data/src/com/sun/hotspot/igv/data/GraphDocument.java

*** 1,7 ****
  /*
!  * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 49,63 ****
--- 49,65 ----
      public ChangedEvent<GraphDocument> getChangedEvent() {
          return changedEvent;
      }
  
      public void addGraphDocument(GraphDocument document) {
+         if (document != this) {
              for (FolderElement e : document.elements) {
                  e.setParent(this);
                  this.addElement(e);
              }
              document.clear();
+         }
          getChangedEvent().fire();
      }
  
      @Override
      public String toString() {