Use WeakHashMap in the static mapping from contexts to vbo trackers in VBOTracker.java.

src/java/org/lwjgl/opengl/GLContext.java

@@ -252,7 +252,7 @@ public final class GLContext {
 			GL11.initNativeStubs();
 			loadStubs();
 			currentContext = new WeakReference(context);
-			VBOTracker.setCurrent(currentContext);
+			VBOTracker.setCurrent(context);
 		} catch (LWJGLException e) {
 			if (did_auto_load)
 				unloadOpenGLLibrary();

src/java/org/lwjgl/opengl/Pbuffer.java

@@ -244,7 +244,6 @@ public final class Pbuffer {
 	 * the current rendering context or not.
 	 */
 	public synchronized void destroy() {
-		VBOTracker.remove(this);
 		try {
 			makeCurrent();
 			int error = GL11.glGetError();

src/java/org/lwjgl/opengl/VBOTracker.java

@@ -31,7 +31,7 @@
  */
 package org.lwjgl.opengl;
 
-import java.util.HashMap;
+import java.util.WeakHashMap;
 import java.util.Map;
 
 /**
@@ -40,7 +40,7 @@ import java.util.Map;
 class VBOTracker {
 	private static VBOTracker current_tracker = null;
 	
-	private static final Map contextToTracker = new HashMap(3, 1.0f);
+	private static final Map contextToTracker = new WeakHashMap(3, 1.0f);
 
 	private final StateStack vbo_array_stack;
 	private final StateStack vbo_element_stack;
@@ -77,15 +77,4 @@ class VBOTracker {
 			contextToTracker.put(context, current_tracker);
 		}
 	}
-	
-	/**
-	 * Remove a context when it is about to be destroyed.
-	 * @param context
-	 */
-	static synchronized void remove(Object context) {
-		contextToTracker.remove(context);
-		if (current_tracker == context) {
-			current_tracker = null;
-		}
-	}
 }