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diff --git a/src/net/java/games/jogl/impl/GLContextStack.java b/src/net/java/games/jogl/impl/GLContextStack.java
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+++ b/src/net/java/games/jogl/impl/GLContextStack.java
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+/*
+ * Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * - Redistribution of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ * - Redistribution in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * 
+ * Neither the name of Sun Microsystems, Inc. or the names of
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ * 
+ * This software is provided "AS IS," without a warranty of any kind. ALL
+ * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
+ * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
+ * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
+ * MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
+ * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
+ * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
+ * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
+ * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
+ * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
+ * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
+ * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+ * 
+ * You acknowledge that this software is not designed or intended for use
+ * in the design, construction, operation or maintenance of any nuclear
+ * facility.
+ * 
+ * Sun gratefully acknowledges that this software was originally authored
+ * and developed by Kenneth Bradley Russell and Christopher John Kline.
+ */
+
+package net.java.games.jogl.impl;
+
+import java.util.*;
+
+/** Implements a stack of GLContext objects along with the initActions
+    that need to be run if their creation is necessary. This is used
+    to detect redundant makeCurrent() calls and to allow one drawable
+    to call display() of another from within the first drawable's
+    display() method. */
+
+public class GLContextStack {
+  private ArrayList data = new ArrayList();
+
+  /** Pushes this GLContext on the stack. The passed context must be non-null. */
+  public void push(GLContext ctx, Runnable initAction) {
+    if (ctx == null) {
+      throw new IllegalArgumentException("Null contexts are not allowed here");
+    }
+
+    data.add(new GLContextInitActionPair(ctx, initAction));
+  }
+
+  /** Removes and returns the top GLContext and associated
+      initialization action, or null if there is none. */
+  public GLContextInitActionPair pop() {
+    if (data.size() == 0) {
+      return null;
+    }
+    
+    return (GLContextInitActionPair) data.remove(data.size() - 1);
+  }
+
+  /** Returns the top GLContext and associated initialization action
+      without removing it, or null if there is none. */
+  public GLContextInitActionPair peek() {
+    return peek(0);
+  }
+
+  /** Returns the <i>i</i>th GLContext and associated initialization
+      action from the top without removing it, or null if there is
+      none. */
+  public GLContextInitActionPair peek(int i) {
+    if (data.size() - i <= 0) {
+      return null;
+    }
+
+    return (GLContextInitActionPair) data.get(data.size() - i - 1);
+  }
+
+  /** Returns the top GLContext without removing it, or null if there
+      is none. */
+  public GLContext peekContext() {
+    return peekContext(0);
+  }
+
+  /** Returns the <i>i</i>th GLContext from the top without removing
+      it, or null if there is none. */
+  public GLContext peekContext(int i) {
+    GLContextInitActionPair pair = peek(i);
+    if (pair == null) {
+      return null;
+    }
+
+    return pair.getContext();
+  }
+
+  /** Returns the top initialization action without removing it, or
+      null if there is none. */
+  public Runnable peekInitAction() {
+    return peekInitAction(0);
+  }
+
+  /** Returns the <i>i</i>th initialization action from the top
+      without removing it, or null if there is none. */
+  public Runnable peekInitAction(int i) {
+    GLContextInitActionPair pair = peek(i);
+    if (pair == null) {
+      return null;
+    }
+
+    return pair.getInitAction();
+  }
+
+  /** Returns the number of entries on the GLContext stack. */
+  public int size() {
+    return data.size();
+  }
+}