Workaround for Bug 623: Sporadic XCB assertion failures w/ ATI proprietary driver and w/o native X11 locking

The proprietary ATI X11 driver does not handle multi-threaded [GL] clients well,
i.e. triggers an XCB assertion 'from time to time'.

It almost seems like that the driver either:
  - aliases all display connections to it's connection name, i.e. server; or
  - utilizes a build-in display connection w/o locking, used for some reason

+++

- X11Lib: Add QueryExtension(dpy, name) allowing early driver determination w/o GL

- X11Util detects 'requiresGlobalToolkitLock' and 'markAllDisplaysUnclosable' via
  X11 extensions. In case certain ATI extensions are available, both are set to true.

- X11GLXDrawableFactory: Dropped setting 'markAllDisplaysUnclosable', using X11Util's detection (see above).

- New GlobalToolkitLock to satisfy certain driver restrictions (ATI's XCB multithreading bug)

- NativeWindowFactory handles new property requiresGlobalToolkitLock,
  in which case the new GlobalToolkitLock is being used instead of ResourceToolkitLock.

- JAWTUtil ToolkitLock locks GlobalToolkitLock 1st to match new 'requiresGlobalToolkitLock' property.

- Document static method requirement of X11Util, GDIUtil and OSXUtil via marker interface ToolkitProperties

- ToolkitLock: New method 'validateLocked()', allowing use to validate whether the device/toolkit
  is properly locked and hence to detect implementation bugs. See unit test class: ValidateLockListener

10 files changed, 270 insertions, 32 deletions

diff --git a/src/nativewindow/classes/jogamp/nativewindow/GlobalToolkitLock.java b/src/nativewindow/classes/jogamp/nativewindow/GlobalToolkitLock.java
new file mode 100644
index 000000000..0c2a1e43f
--- /dev/null
+++ b/src/nativewindow/classes/jogamp/nativewindow/GlobalToolkitLock.java
@@ -0,0 +1,75 @@
+/**
+ * Copyright 2012 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ *
+ *    2. Redistributions 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+
+package jogamp.nativewindow;
+
+import javax.media.nativewindow.ToolkitLock;
+
+import com.jogamp.common.util.locks.LockFactory;
+import com.jogamp.common.util.locks.RecursiveLock;
+
+/**
+ * Implementing a global recursive {@link javax.media.nativewindow.ToolkitLock}.
+ * <p>
+ * This is the last resort for unstable driver, e.g. proprietary ATI/X11 12.8 and 12.9,
+ * where multiple X11 display connections to the same connection name are not treated
+ * thread safe within the GL/X11 driver.
+ * </p>
+ */
+public class GlobalToolkitLock implements ToolkitLock {
+    private static final RecursiveLock globalLock = LockFactory.createRecursiveLock();
+    
+    /** Singleton via {@link NativeWindowFactoryImpl#getGlobalToolkitLock()} */
+    protected GlobalToolkitLock() { }
+    
+    @Override
+    public final void lock() {
+        globalLock.lock();
+        if(TRACE_LOCK) { System.err.println("GlobalToolkitLock.lock()"); }
+    }
+
+    @Override
+    public final void unlock() {
+        if(TRACE_LOCK) { System.err.println("GlobalToolkitLock.unlock()"); }
+        globalLock.unlock(); // implicit lock validation
+    }
+    
+    @Override
+    public final void validateLocked() throws RuntimeException {
+        globalLock.validateLocked();
+    }
+    
+    @Override
+    public final void dispose() {
+        // nop
+    }
+    
+    public String toString() {
+        return "GlobalToolkitLock[obj 0x"+Integer.toHexString(hashCode())+", isOwner "+globalLock.isOwner(Thread.currentThread())+", "+globalLock.toString()+"]";
+    }
+}
diff --git a/src/nativewindow/classes/jogamp/nativewindow/NativeWindowFactoryImpl.java b/src/nativewindow/classes/jogamp/nativewindow/NativeWindowFactoryImpl.java
index 29564da3b..c35cede77 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/NativeWindowFactoryImpl.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/NativeWindowFactoryImpl.java
@@ -44,9 +44,14 @@ import com.jogamp.common.util.ReflectionUtil.AWTNames;
 
 public class NativeWindowFactoryImpl extends NativeWindowFactory {
     private static final ToolkitLock nullToolkitLock = new NullToolkitLock();
+    private static final ToolkitLock globalToolkitLock = new GlobalToolkitLock();
 
     public static ToolkitLock getNullToolkitLock() {
-            return nullToolkitLock;
+        return nullToolkitLock;
+    }
+    
+    public static ToolkitLock getGlobalToolkitLock() {
+        return globalToolkitLock;
     }
     
     // This subclass of NativeWindowFactory handles the case of
diff --git a/src/nativewindow/classes/jogamp/nativewindow/NullToolkitLock.java b/src/nativewindow/classes/jogamp/nativewindow/NullToolkitLock.java
index e59910138..211e15955 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/NullToolkitLock.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/NullToolkitLock.java
@@ -31,15 +31,16 @@ package jogamp.nativewindow;
 import javax.media.nativewindow.ToolkitLock;
 
 /**
- * Implementing a singleton global recursive {@link javax.media.nativewindow.ToolkitLock}
- * without any locking. Since there is no locking it all,
- * it is intrinsically recursive.
+ * Implementing a singleton global NOP {@link javax.media.nativewindow.ToolkitLock}
+ * without any locking. Since there is no locking it all, it is intrinsically recursive.
  */
 public class NullToolkitLock implements ToolkitLock {
-
+    public static final boolean INVALID_LOCKED = Debug.isPropertyDefined("nativewindow.debug.NullToolkitLock.InvalidLocked", true);
+    
     /** Singleton via {@link NativeWindowFactoryImpl#getNullToolkitLock()} */
     protected NullToolkitLock() { }
     
+    @Override
     public final void lock() {
         if(TRACE_LOCK) {
             System.err.println("NullToolkitLock.lock()");
@@ -47,10 +48,20 @@ public class NullToolkitLock implements ToolkitLock {
         }
     }
 
+    @Override
     public final void unlock() {
         if(TRACE_LOCK) { System.err.println("NullToolkitLock.unlock()"); }
     }
     
+    @Override
+    public final void validateLocked() throws RuntimeException {
+        /* nop */
+        if(INVALID_LOCKED) {
+            throw new RuntimeException("NullToolkitLock does not lock");
+        }
+    }
+    
+    @Override
     public final void dispose() {
         // nop
     }
diff --git a/src/nativewindow/classes/jogamp/nativewindow/ResourceToolkitLock.java b/src/nativewindow/classes/jogamp/nativewindow/ResourceToolkitLock.java
index a3b0804fa..5b79de0b8 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/ResourceToolkitLock.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/ResourceToolkitLock.java
@@ -41,8 +41,6 @@ import com.jogamp.common.util.locks.RecursiveLock;
  * </p>
  */
 public class ResourceToolkitLock implements ToolkitLock {
-    public static final boolean DEBUG = Debug.debug("ToolkitLock");
-    
     public static final ResourceToolkitLock create() {
         return new ResourceToolkitLock();
     }
@@ -53,17 +51,24 @@ public class ResourceToolkitLock implements ToolkitLock {
         this.lock = LockFactory.createRecursiveLock();
     }
     
-    
+    @Override
     public final void lock() {
-        if(TRACE_LOCK) { System.err.println("ResourceToolkitLock.lock()"); }
         lock.lock();
+        if(TRACE_LOCK) { System.err.println("ResourceToolkitLock.lock()"); }
     }
 
+    @Override
     public final void unlock() {
         if(TRACE_LOCK) { System.err.println("ResourceToolkitLock.unlock()"); }
-        lock.unlock();
+        lock.unlock(); // implicit lock validation
+    }
+    
+    @Override
+    public final void validateLocked() throws RuntimeException {
+        lock.validateLocked();
     }
     
+    @Override
     public final void dispose() {
         // nop
     }
diff --git a/src/nativewindow/classes/jogamp/nativewindow/SharedResourceToolkitLock.java b/src/nativewindow/classes/jogamp/nativewindow/SharedResourceToolkitLock.java
index 5d7ae8abb..94d12e6fc 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/SharedResourceToolkitLock.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/SharedResourceToolkitLock.java
@@ -49,7 +49,6 @@ import com.jogamp.common.util.locks.RecursiveLock;
  * </p>
  */
 public class SharedResourceToolkitLock implements ToolkitLock {
-    public static final boolean DEBUG = Debug.debug("ToolkitLock");
     private static final LongObjectHashMap handle2Lock;
     static {
         handle2Lock = new LongObjectHashMap();
@@ -109,16 +108,24 @@ public class SharedResourceToolkitLock implements ToolkitLock {
     }
     
     
+    @Override
     public final void lock() {
-        if(TRACE_LOCK) { System.err.println("SharedResourceToolkitLock.lock()"); }
         lock.lock();
+        if(TRACE_LOCK) { System.err.println("SharedResourceToolkitLock.lock()"); }
     }
 
+    @Override
     public final void unlock() {
         if(TRACE_LOCK) { System.err.println("SharedResourceToolkitLock.unlock()"); }
         lock.unlock();
     }
     
+    @Override
+    public final void validateLocked() throws RuntimeException {
+        lock.validateLocked();
+    }
+    
+    @Override
     public final void dispose() {
         if(0 < refCount) { // volatile OK
             synchronized(handle2Lock) {
diff --git a/src/nativewindow/classes/jogamp/nativewindow/ToolkitProperties.java b/src/nativewindow/classes/jogamp/nativewindow/ToolkitProperties.java
new file mode 100644
index 000000000..2062d1f58
--- /dev/null
+++ b/src/nativewindow/classes/jogamp/nativewindow/ToolkitProperties.java
@@ -0,0 +1,51 @@
+package jogamp.nativewindow;
+
+import javax.media.nativewindow.NativeWindowFactory;
+
+/**
+ * Marker interface.
+ * <p>
+ * Implementation requires to provide static methods:
+ * <pre>
+    public static void initSingleton() {}
+    
+    public static void shutdown() {}
+    
+    public static boolean requiresToolkitLock() {}
+    
+    public static boolean requiresGlobalToolkitLock() {}
+ * </pre>
+ * Above static methods are invoked by {@link NativeWindowFactory#initSingleton()}, 
+ * or {@link NativeWindowFactory#shutdown()} via reflection.
+ * </p>
+ * <p>
+ * If <code>requiresGlobalToolkitLock() == true</code>, then 
+ * <code>requiresToolkitLock() == true</code> shall be valid as well.
+ * </p>
+ */
+public interface ToolkitProperties {
+
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     */
+    // void initSingleton();
+    
+    /** 
+     * Cleanup resources.
+     * <p>
+     * Called by {@link NativeWindowFactory#shutdown()}
+     * </p>
+     */
+    // void shutdown();
+    
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     */
+    // boolean requiresToolkitLock();
+    
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     */
+    // boolean requiresGlobalToolkitLock();    
+    
+}
diff --git a/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java b/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
index 7c934b154..2dadfb16b 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
@@ -79,6 +79,8 @@ public class JAWTUtil {
   private static final Method  sunToolkitAWTLockMethod;
   private static final Method  sunToolkitAWTUnlockMethod;
   private static final boolean hasSunToolkitAWTLock;
+  
+  private static volatile Thread exclusiveOwnerThread;
 
   private static final ToolkitLock jawtToolkitLock;
 
@@ -229,13 +231,23 @@ public class JAWTUtil {
     }
     hasSunToolkitAWTLock = _hasSunToolkitAWTLock;
     // hasSunToolkitAWTLock = false;
+    exclusiveOwnerThread = null;
 
     jawtToolkitLock = new ToolkitLock() {
           public final void lock() {
+              NativeWindowFactory.getGlobalToolkitLock().lock();
               JAWTUtil.lockToolkit();
+              if(TRACE_LOCK) { System.err.println("JAWTToolkitLock.lock()"); }
           }    
           public final void unlock() {
+              if(TRACE_LOCK) { System.err.println("JAWTToolkitLock.unlock()"); }
               JAWTUtil.unlockToolkit();
+              NativeWindowFactory.getGlobalToolkitLock().unlock();
+          }
+          @Override
+          public final void validateLocked() throws RuntimeException {
+              NativeWindowFactory.getGlobalToolkitLock().validateLocked();
+              JAWTUtil.validateLocked();
           }
           public final void dispose() {
               // nop
@@ -312,7 +324,7 @@ public class JAWTUtil {
    * JAWT's native Lock() function calls SunToolkit.awtLock(),
    * which just uses AWT's global ReentrantLock.<br>
    */
-  private static void awtLock() {
+  private static final void awtLock() {
     if(hasSunToolkitAWTLock) {
         try {
             sunToolkitAWTLockMethod.invoke(null, (Object[])null);
@@ -322,6 +334,7 @@ public class JAWTUtil {
     } else {
         jawtLockObject.Lock();
     }
+    exclusiveOwnerThread = Thread.currentThread();
   }
 
   /**
@@ -330,7 +343,9 @@ public class JAWTUtil {
    * JAWT's native Unlock() function calls SunToolkit.awtUnlock(),
    * which just uses AWT's global ReentrantLock.<br>
    */
-  private static void awtUnlock() {
+  private static final void awtUnlock() {
+    awtValidateLocked();
+    exclusiveOwnerThread = null;    
     if(hasSunToolkitAWTLock) {
         try {
             sunToolkitAWTUnlockMethod.invoke(null, (Object[])null);
@@ -342,6 +357,16 @@ public class JAWTUtil {
     }
   }
 
+  private static final void awtValidateLocked() throws RuntimeException {
+    final Thread ct = Thread.currentThread();
+    if( ct != exclusiveOwnerThread ) {
+        if ( null == exclusiveOwnerThread ) {
+            throw new RuntimeException(ct.getName()+": JAWT-ToolkitLock not locked");
+        }
+        throw new RuntimeException(ct.getName()+": Not JAWT-ToolkitLock owner. Owner is "+exclusiveOwnerThread.getName());
+    }
+  }
+  
   public static void lockToolkit() throws NativeWindowException {
     if(ToolkitLock.TRACE_LOCK) { System.err.println("JAWTUtil-ToolkitLock.lock()"); }
     if(!headlessMode && !isJava2DQueueFlusherThread()) {
@@ -355,6 +380,13 @@ public class JAWTUtil {
         awtUnlock();
     }
   }
+  
+  public static final void validateLocked() throws RuntimeException {
+    if(!headlessMode && !isJava2DQueueFlusherThread()) {
+        awtValidateLocked();
+    }
+  }
+  
 
   public static ToolkitLock getJAWTToolkitLock() {
     return jawtToolkitLock;
diff --git a/src/nativewindow/classes/jogamp/nativewindow/macosx/OSXUtil.java b/src/nativewindow/classes/jogamp/nativewindow/macosx/OSXUtil.java
index b7a83e133..481cbbe39 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/macosx/OSXUtil.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/macosx/OSXUtil.java
@@ -34,13 +34,15 @@ import javax.media.nativewindow.util.Point;
 
 import jogamp.nativewindow.Debug;
 import jogamp.nativewindow.NWJNILibLoader;
+import jogamp.nativewindow.ToolkitProperties;
 
-public class OSXUtil {
+public class OSXUtil implements ToolkitProperties {
     private static boolean isInit = false;  
     private static final boolean DEBUG = Debug.debug("OSXUtil");
     
     /**
      * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
      */
     public static synchronized void initSingleton() {
       if(!isInit) {
@@ -60,13 +62,21 @@ public class OSXUtil {
 
     /**
      * Called by {@link NativeWindowFactory#shutdown()}
+     * @see ToolkitProperties
      */
-    public static void shutdown() {      
-    }
+    public static void shutdown() { }
     
-    public static boolean requiresToolkitLock() {
-        return false;
-    }
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
+    public static boolean requiresToolkitLock() { return false; }
+    
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
+    public static final boolean requiresGlobalToolkitLock() { return false; }
     
     public static boolean isNSView(long object) {
         return isNSView0(object);
diff --git a/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java b/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
index 613c76032..4408a0903 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
@@ -33,9 +33,10 @@ import javax.media.nativewindow.NativeWindowFactory;
 
 import jogamp.nativewindow.NWJNILibLoader;
 import jogamp.nativewindow.Debug;
+import jogamp.nativewindow.ToolkitProperties;
 import jogamp.nativewindow.x11.X11Util;
 
-public class GDIUtil {
+public class GDIUtil implements ToolkitProperties {
     private static final boolean DEBUG = Debug.debug("GDIUtil");
   
     private static final String dummyWindowClassNameBase = "_dummyWindow_clazz" ;
@@ -44,6 +45,7 @@ public class GDIUtil {
   
     /**
      * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
      */
     public static synchronized void initSingleton() {
         if(!isInit) {
@@ -67,12 +69,23 @@ public class GDIUtil {
   
     /**
      * Called by {@link NativeWindowFactory#shutdown()}
+     * @see ToolkitProperties
      */
     public static void shutdown() {      
     }
     
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
     public static boolean requiresToolkitLock() { return false; }
   
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
+    public static final boolean requiresGlobalToolkitLock() { return false; }
+    
     private static RegisteredClass dummyWindowClass = null;
     private static Object dummyWindowSync = new Object();
   
diff --git a/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java b/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
index 30792113d..a331fa940 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
@@ -43,13 +43,15 @@ import javax.media.nativewindow.NativeWindowFactory;
 
 import jogamp.nativewindow.Debug;
 import jogamp.nativewindow.NWJNILibLoader;
+import jogamp.nativewindow.ToolkitProperties;
+
 import com.jogamp.common.util.LongObjectHashMap;
 import com.jogamp.nativewindow.x11.X11GraphicsDevice;
 
 /**
  * Contains a thread safe X11 utility to retrieve display connections.
  */
-public class X11Util {
+public class X11Util implements ToolkitProperties {
     /** 
      * See Bug 515 - https://jogamp.org/bugzilla/show_bug.cgi?id=515
      * <p> 
@@ -88,11 +90,15 @@ public class X11Util {
     private static String nullDisplayName = null;
     private static volatile boolean isInit = false;
     private static boolean markAllDisplaysUnclosable = false; // ATI/AMD X11 driver issues
+    private static boolean requiresGlobalToolkitLock = false; // ATI/AMD X11 driver issues
 
     private static Object setX11ErrorHandlerLock = new Object();
+    private static final String X11_EXTENSION_ATIFGLRXDRI     = "ATIFGLRXDRI";
+    private static final String X11_EXTENSION_ATIFGLEXTENSION = "ATIFGLEXTENSION";
     
     /**
      * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
      */
     public static void initSingleton() {
         if(!isInit) {
@@ -100,7 +106,7 @@ public class X11Util {
                 if(!isInit) {
                     isInit = true;
                     if(DEBUG) {
-                        System.out.println("X11UtilUtil.initSingleton()");
+                        System.out.println("X11Util.initSingleton()");
                     }
                     if(!NWJNILibLoader.loadNativeWindow("x11")) {
                         throw new NativeWindowException("NativeWindow X11 native library load error.");
@@ -108,6 +114,7 @@ public class X11Util {
         
                     final boolean isInitOK = initialize0( XERROR_STACKDUMP );
         
+                    final boolean hasX11_EXTENSION_ATIFGLRXDRI, hasX11_EXTENSION_ATIFGLEXTENSION;
                     final long dpy = X11Lib.XOpenDisplay(null);
                     if(0 != dpy) {
                         if(XSYNC_ENABLED) {
@@ -115,17 +122,29 @@ public class X11Util {
                         }                    
                         try {
                             nullDisplayName = X11Lib.XDisplayString(dpy);
+                            hasX11_EXTENSION_ATIFGLRXDRI = X11Lib.QueryExtension(dpy, X11_EXTENSION_ATIFGLRXDRI);
+                            hasX11_EXTENSION_ATIFGLEXTENSION = X11Lib.QueryExtension(dpy, X11_EXTENSION_ATIFGLEXTENSION);
                         } finally {
                             X11Lib.XCloseDisplay(dpy);
                         }
                     } else {
                         nullDisplayName = "nil";
+                        hasX11_EXTENSION_ATIFGLRXDRI = false;
+                        hasX11_EXTENSION_ATIFGLEXTENSION = false;
                     }
+                    requiresGlobalToolkitLock = hasX11_EXTENSION_ATIFGLRXDRI || hasX11_EXTENSION_ATIFGLEXTENSION;
+                    markAllDisplaysUnclosable = ATI_HAS_XCLOSEDISPLAY_BUG && ( hasX11_EXTENSION_ATIFGLRXDRI || hasX11_EXTENSION_ATIFGLEXTENSION );
                     
                     if(DEBUG) {
-                        System.err.println("X11Util init OK "+isInitOK+"]"+
-                                           ", X11 Display(NULL) <"+nullDisplayName+">"+
-                                           ", XSynchronize Enabled: "+XSYNC_ENABLED);
+                        System.err.println("X11Util.initSingleton(): OK "+isInitOK+"]"+
+                                           ",\n\t X11 Display(NULL) <"+nullDisplayName+">"+
+                                           ",\n\t XSynchronize Enabled: " + XSYNC_ENABLED+
+                                           ",\n\t X11_EXTENSION_ATIFGLRXDRI " + hasX11_EXTENSION_ATIFGLRXDRI+
+                                           ",\n\t X11_EXTENSION_ATIFGLEXTENSION " + hasX11_EXTENSION_ATIFGLEXTENSION+
+                                           ",\n\t requiresToolkitLock "+requiresToolkitLock()+
+                                           ",\n\t requiresGlobalToolkitLock "+requiresGlobalToolkitLock()+
+                                           ",\n\t markAllDisplaysUnclosable "+getMarkAllDisplaysUnclosable()
+                                           );
                         // Thread.dumpStack();
                     }
                 }
@@ -147,6 +166,7 @@ public class X11Util {
      * <p>
      * Called by {@link NativeWindowFactory#shutdown()}
      * </p>
+     * @see ToolkitProperties
      */
     public static void shutdown() {
         if(isInit) {
@@ -189,8 +209,20 @@ public class X11Util {
         }
     }
     
-    public static boolean requiresToolkitLock() {
-        return true; // JAWT locking: yes, instead of native X11 locking w use a recursive lock.
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
+    public static final boolean requiresToolkitLock() {
+        return true; // JAWT locking: yes, instead of native X11 locking w use a recursive lock per display connection.
+    }
+    
+    /**
+     * Called by {@link NativeWindowFactory#initSingleton()}
+     * @see ToolkitProperties
+     */
+    public static final boolean requiresGlobalToolkitLock() {
+        return requiresGlobalToolkitLock; // JAWT locking: yes, instead of native X11 locking w use a global lock.
     }
     
     public static void setX11ErrorHandler(boolean onoff, boolean quiet) {
@@ -206,9 +238,6 @@ public class X11Util {
     public static boolean getMarkAllDisplaysUnclosable() {
         return markAllDisplaysUnclosable;
     }
-    public static void setMarkAllDisplaysUnclosable(boolean v) {
-        markAllDisplaysUnclosable = v;
-    }
     
     private X11Util() {}
 
@@ -373,7 +402,7 @@ public class X11Util {
         name = validateDisplayName(name);
         boolean reused = false;
         
-        synchronized(globalLock) {            
+        synchronized(globalLock) {
             for(int i=0; i<reusableDisplayList.size(); i++) {
                 if(reusableDisplayList.get(i).getName().equals(name)) {
                     namedDpy = reusableDisplayList.remove(i);