Bug 907 - Refine DummyDispatchThread (DDT) Handling: Proper OO integration in RegisteredClass; Safe DDT Post/WaitForReady handling and error cases ; ...

Proper OO integration of DDT in RegisteredClass
  - DDT is optional to RegisteredClass[Factory],
    i.e. NEWT without DDT and DummyWindow with DDT.

  - Using native type DummyThreadContext per DDT
    passed as DDT handle to java referenced in RegisteredClass

  - Passing DDT handle to related native methods,
    if not null use DDT - otherwise work on current thread.
    The latter impacts CreateDummyWindow0 and DestroyWindow0.

Safe DDT Post/WaitForReady handling and error cases ; ...
  - Wait until command it complete using a 3s timeout
  - Terminate thread if errors occur and throw an exception

+++

Discussion: DDT Native Implementation

Due to original code, the DDT is implemented in native code.
Usually we should favor running the DDT from a java thread.
However, since it's main purpose is _not_ to interact w/ java
and the native implementation has less footprint (performance and memory)
we shall be OK w/ it for now - as long the implementation IS SAFE.

10 files changed, 373 insertions, 192 deletions

diff --git a/make/scripts/tests-win.bat b/make/scripts/tests-win.bat
index fb224c882..d95b0025f 100755
--- a/make/scripts/tests-win.bat
+++ b/make/scripts/tests-win.bat
@@ -6,7 +6,7 @@ REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.acore.TestMainVersion
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.newt.TestGearsNewtAWTWrapper %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.newt.TestGearsNEWT -time 30000
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es1.newt.TestGearsES1NEWT %*
-REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT %*
+scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT -vsync -time 4000 -x 10 -y 10 -width 100 -height 100 -screen 0
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT -vsync -time 40000 -width 100 -height 100 -screen 0 %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsAWT -time 5000
@@ -18,7 +18,7 @@ REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestLa
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestElektronenMultipliziererNEWT %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.gl3.newt.TestGeomShader01TextureGL3NEWT %*
 
-scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieSimple %*
+REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieSimple %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieCube %*
 REM scripts\java-win.bat com.jogamp.opengl.test.junit.jogl.demos.es2.TexCubeES2 %*
 
diff --git a/make/scripts/tests-x64-dbg.bat b/make/scripts/tests-x64-dbg.bat
index 851c1dbec..3e56a31a6 100755
--- a/make/scripts/tests-x64-dbg.bat
+++ b/make/scripts/tests-x64-dbg.bat
@@ -21,16 +21,18 @@ set CP_ALL=.;%BLD_DIR%\jar\jogl-all.jar;%BLD_DIR%\jar\jogl-test.jar;..\..\joal\%
 echo CP_ALL %CP_ALL%

 

 REM set D_ARGS="-Djogamp.debug=all"

+set D_ARGS="-Djogl.debug=all" "-Dnativewindow.debug=all"

+REM set D_ARGS="-Djogl.debug=all" "-Dnewt.debug=all" "-Dnativewindow.debug=all"

+REM set D_ARGS="-Djogl.debug=all" "-Dnewt.debug=all" "-Dnativewindow.debug=all" "-Djogamp.debug=all" "-Djogl.debug.EGLDrawableFactory.DontQuery"

+REM set D_ARGS="-Dnativewindow.debug.GDIUtil" "-Dnativewindow.debug.RegisteredClass"

 REM set D_ARGS="-Djogl.debug.GLContext" "-Djogl.debug.FBObject"

 REM set D_ARGS="-Djogl.debug.GLDrawable" "-Djogl.debug.EGLDrawableFactory.DontQuery"

 REM set D_ARGS="-Djogl.debug.GLDrawable" "-Djogl.debug.EGLDrawableFactory.QueryNativeTK"

-REM set D_ARGS="-Djogl.debug=all" "-Dnewt.debug=all" "-Dnativewindow.debug=all"

 REM set D_ARGS="-Djogl.debug.GLDrawable" "-Djogl.debug.GLContext" "-Djogl.debug.GLCanvas"

-REM set D_ARGS="-Djogl.debug=all" "-Dnewt.debug=all" "-Dnativewindow.debug=all" "-Djogamp.debug=all" "-Djogl.debug.EGLDrawableFactory.DontQuery"

 REM set D_ARGS="-Dnativewindow.debug.GraphicsConfiguration -Djogl.debug.CapabilitiesChooser -Djogl.debug.GLProfile"

 REM set D_ARGS="-Djogamp.debug.IOUtil"

 REM set D_ARGS="-Djogl.debug.GLSLCode" "-Djogl.debug.GLMediaPlayer"

-set D_ARGS="-Djogl.debug.GLMediaPlayer"

+REM set D_ARGS="-Djogl.debug.GLMediaPlayer"

 REM set D_ARGS="-Djogl.debug.GLMediaPlayer" "-Djogl.debug.AudioSink"

 REM set D_ARGS="-Djogl.debug.GLMediaPlayer" "-Djogl.debug.GLMediaPlayer.Native"

 REM set D_ARGS="-Djogl.debug.GLMediaPlayer.StreamWorker.delay=25" "-Djogl.debug.GLMediaPlayer"

diff --git a/make/scripts/tests.sh b/make/scripts/tests.sh
index ce8005821..56a07e768 100644
--- a/make/scripts/tests.sh
+++ b/make/scripts/tests.sh
@@ -84,6 +84,17 @@ function jrun() {
     #D_ARGS="-Djogl.debug.DebugGL"
     #D_ARGS="-Djogl.debug.TraceGL"
     #D_ARGS="-Djogl.debug.DebugGL -Djogl.debug.TraceGL"
+
+    #D_ARGS="-Djogamp.debug=all"
+    #D_ARGS="-Dnativewindow.debug=all"
+    #D_ARGS="-Djogl.debug=all"
+    #D_ARGS="-Dnewt.debug=all"
+    #D_ARGS="-Djogl.debug=all -Dnewt.debug=all"
+    D_ARGS="-Djogl.debug=all -Dnativewindow.debug=all"
+    #D_ARGS="-Djogamp.debug=all -Dnativewindow.debug=all -Djogl.debug=all -Dnewt.debug=all"
+    #D_ARGS="-Dnativewindow.debug=all -Djogl.debug=all -Dnewt.debug=all"
+    #D_ARGS="-Djogl.debug=all -Dnativewindow.debug=all -Dnewt.debug=all -Djogamp.debug.Lock"
+
     #D_ARGS="-Dnativewindow.debug.X11Util.ATI_HAS_NO_XCLOSEDISPLAY_BUG"
     #D_ARGS="-Dnativewindow.debug.X11Util.ATI_HAS_NO_MULTITHREADING_BUG"
     #D_ARGS="-Djogl.disable.opengles"
@@ -93,7 +104,7 @@ function jrun() {
     #D_ARGS="-Djogl.debug.FBObject"
     #D_ARGS="-Djogl.debug.GLSLCode"
     #D_ARGS="-Djogl.debug.GLSLCode -Djogl.debug.DebugGL"
-    #D_ARGS="-Djogl.debug=all -Dnewt.debug=all"
+    #D_ARGS="-Dnativewindow.debug.X11Util -Dnativewindow.debug.X11Util.TraceDisplayLifecycle -Djogl.debug.EGLDisplayUtil -Djogl.debug.GLDrawable"
     #D_ARGS="-Djogl.debug.GLContext -Dnativewindow.debug.JAWT -Dnewt.debug.Window"
     #D_ARGS="-Dnativewindow.debug.JAWT -Djogamp.debug.TaskBase.TraceSource"
     #D_ARGS="-Djogl.debug.GLContext.TraceSwitch"
@@ -110,10 +121,6 @@ function jrun() {
     #D_ARGS="-Dnativewindow.debug.GraphicsConfiguration"
     #D_ARGS="-Djogl.debug.GLContext"
     #D_ARGS="-Djogl.debug.GLContext.NoProfileAliasing"
-    #D_ARGS="-Djogamp.debug=all"
-    #D_ARGS="-Djogamp.debug=all -Dnativewindow.debug=all -Djogl.debug=all -Dnewt.debug=all"
-    #D_ARGS="-Dnativewindow.debug=all -Djogl.debug=all -Dnewt.debug=all"
-    #D_ARGS="-Dnativewindow.debug.X11Util -Dnativewindow.debug.X11Util.TraceDisplayLifecycle -Djogl.debug.EGLDisplayUtil -Djogl.debug.GLDrawable"
     #D_ARGS="-Djogl.debug.GLDrawable -Dnativewindow.debug.X11Util -Dnativewindow.debug.NativeWindow -Dnewt.debug.Display -Dnewt.debug.Screen -Dnewt.debug.Window"
     #D_ARGS="-Djogl.debug.Animator -Djogl.debug.GLDrawable -Dnativewindow.debug.NativeWindow"
     #D_ARGS="-Djogl.debug=all -Dnewt.debug=all"
@@ -122,8 +129,6 @@ function jrun() {
     #D_ARGS="-Djogl.debug.GLDrawable"
     #D_ARGS="-Djogl.debug.GLEventListenerState"
     #D_ARGS="-Djogl.fbo.force.none"
-    #D_ARGS="-Djogl.debug=all -Dnativewindow.debug=all -Dnewt.debug=all -Djogamp.debug.Lock"
-    #D_ARGS="-Djogl.debug=all"
     #D_ARGS="-Djogl.debug.EGLDrawableFactory.DontQuery -Djogl.debug.GLDrawable"
     #D_ARGS="-Djogl.debug.EGLDrawableFactory.QueryNativeTK -Djogl.debug.GLDrawable"
     #D_ARGS="-Djogl.debug.GLDebugMessageHandler"
@@ -137,7 +142,7 @@ function jrun() {
     #D_ARGS="-Djogamp.debug.IOUtil -Djogl.debug.GLSLCode -Djogl.debug.GLMediaPlayer"
     #D_ARGS="-Djogl.debug.GLMediaPlayer -Djogl.debug.AudioSink"
     #D_ARGS="-Djogl.debug.GLMediaPlayer -Djogl.debug.GLMediaPlayer.Native"
-    D_ARGS="-Djogl.debug.GLMediaPlayer"
+    #D_ARGS="-Djogl.debug.GLMediaPlayer"
     #D_ARGS="-Djogl.debug.GLMediaPlayer.StreamWorker.delay=25 -Djogl.debug.GLMediaPlayer"
     #D_ARGS="-Djogl.debug.GLMediaPlayer.Native"
     #D_ARGS="-Djogl.debug.AudioSink"
@@ -201,7 +206,6 @@ function jrun() {
     #D_ARGS="-Dnewt.debug.Window -Dnewt.debug.Window.MouseEvent -Dnewt.debug.Window.KeyEvent"
     #D_ARGS="-Dnewt.debug.Window"
     #D_ARGS="-Xprof"
-    #D_ARGS="-Dnativewindow.debug=all"
     #D_ARGS="-Djogl.debug.GLCanvas -Djogl.debug.Java2D -Djogl.debug.GLJPanel"
     #D_ARGS="-Djogl.debug.GLCanvas -Djogl.debug.Java2D -Djogl.debug.GLJPanel -Djogl.gljpanel.noglsl"
     #D_ARGS="-Djogl.debug.GLJPanel -Djogl.debug.DebugGL"
@@ -225,7 +229,6 @@ function jrun() {
     #D_ARGS="-Dnewt.debug=all -Djogamp.debug.Lock -Djogamp.debug.Lock.TraceLock"
     #D_ARGS="-Djogl.debug.GLContext -Dnewt.debug=all -Djogamp.debug.Lock -Djogamp.common.utils.locks.Lock.timeout=10000"
     #D_ARGS="-Djogl.debug.GLContext -Dnewt.debug=all"
-    #D_ARGS="-Dnewt.debug=all"
     #D_ARGS="-Djogl.debug.GLCanvas -Djogl.debug.GLJPanel -Djogl.debug.TileRenderer -Djogl.debug.TileRenderer.PNG"
     #D_ARGS="-Djogl.debug.GLCanvas -Djogl.debug.GLJPanel -Djogl.debug.TileRenderer"
     #D_ARGS="-Djogl.debug.PNGImage"
@@ -322,7 +325,7 @@ function testawtswt() {
 #testawt com.jogamp.opengl.test.junit.jogl.demos.es2.awt.TestGearsES2GLJPanelsAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NewtCanvasAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestLandscapeES2NewtCanvasAWT $*
-#testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT $*
+testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.acore.TestGLProfile00NEWT $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestLandscapeES2NEWT $*
 #testawtswt com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NewtCanvasSWT $*
@@ -345,7 +348,7 @@ function testawtswt() {
 #
 #testnoawt jogamp.opengl.openal.av.ALDummyUsage $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieCube $*
-testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieSimple $*
+#testnoawt com.jogamp.opengl.test.junit.jogl.demos.es2.av.MovieSimple $*
 
 #
 # performance tests
diff --git a/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java b/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
index bab4b5c6e..a872e63d8 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/windows/GDIUtil.java
@@ -59,7 +59,7 @@ public class GDIUtil implements ToolkitProperties {
                     if( !initIDs0() ) {
                         throw new NativeWindowException("GDI: Could not initialized native stub");
                     }
-                    dummyWindowClassFactory = new RegisteredClassFactory(dummyWindowClassNameBase, getDummyWndProc0());
+                    dummyWindowClassFactory = new RegisteredClassFactory(dummyWindowClassNameBase, getDummyWndProc0(), true /* useDummyDispatchThread */);
                     if(DEBUG) {
                         System.out.println("GDI.initSingleton() dummyWindowClassFactory "+dummyWindowClassFactory);
                     }
@@ -98,8 +98,7 @@ public class GDIUtil implements ToolkitProperties {
                 System.out.println("GDI.CreateDummyWindow() dummyWindowClassFactory "+dummyWindowClassFactory);
                 System.out.println("GDI.CreateDummyWindow() dummyWindowClass "+dummyWindowClass);
             }
-            // FIXME return CreateDummyWindow0(dummyWindowClass.getHInstance(), dummyWindowClass.getName(), dummyWindowClass.getName(), x, y, width, height);
-            return CreateDummyWindowAndMessageLoop(dummyWindowClass.getHInstance(), dummyWindowClass.getName(), dummyWindowClass.getName(), x, y, width, height);
+            return CreateDummyWindow0(dummyWindowClass.getHInstance(), dummyWindowClass.getName(), dummyWindowClass.getHDispThreadContext(), dummyWindowClass.getName(), x, y, width, height);
         }
     }
 
@@ -109,8 +108,7 @@ public class GDIUtil implements ToolkitProperties {
             if( null == dummyWindowClass ) {
                 throw new InternalError("GDI Error ("+dummyWindowClassFactory.getSharedRefCount()+"): SharedClass is null");
             }
-            // FIXME res = GDI.DestroyWindow(hwnd);
-            res = SendCloseMessage(hwnd);
+            res = DestroyWindow0(dummyWindowClass.getHDispThreadContext(), hwnd);
             dummyWindowClassFactory.releaseSharedClass();
         }
         return res;
@@ -128,8 +126,11 @@ public class GDIUtil implements ToolkitProperties {
         return IsChild0(win);
     }
 
-    public static native boolean CreateWindowClass(long hInstance, String clazzName, long wndProc);
-    public static native boolean DestroyWindowClass(long hInstance, String className);
+    private static final void dumpStack() { Thread.dumpStack(); } // Callback for JNI
+
+    static native boolean CreateWindowClass0(long hInstance, String clazzName, long wndProc);
+    static native boolean DestroyWindowClass0(long hInstance, String className, long dispThreadCtx);
+    static native long CreateDummyDispatchThread0();
 
     private static native boolean initIDs0();
     private static native long getDummyWndProc0();
@@ -137,8 +138,6 @@ public class GDIUtil implements ToolkitProperties {
     private static native boolean IsChild0(long win);
     private static native boolean IsUndecorated0(long win);
 
-    private static native long CreateDummyWindow0(long hInstance, String className, String windowName, int x, int y, int width, int height);
-
-    private static native long CreateDummyWindowAndMessageLoop(long hInstance, String className, String windowName, int x, int y, int width, int height);
-    private static native boolean SendCloseMessage(long win);
+    private static native long CreateDummyWindow0(long hInstance, String className, long dispThreadCtx, String windowName, int x, int y, int width, int height);
+    private static native boolean DestroyWindow0(long dispThreadCtx, long win);
 }
diff --git a/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClass.java b/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClass.java
index 976693e3a..1f6cb7c05 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClass.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClass.java
@@ -29,12 +29,14 @@
 package jogamp.nativewindow.windows;
 
 public class RegisteredClass {
-    long hInstance;
-    String className;
+    private final long hInstance;
+    private final String className;
+    private final long hDDTCtx;
 
-    RegisteredClass(long hInst, String name) {
-        hInstance = hInst;
-        className = name;
+    RegisteredClass(long hInst, String name, long hDispatchThreadCtx) {
+        this.hInstance = hInst;
+        this.className = name;
+        this.hDDTCtx = hDispatchThreadCtx;
     }
 
     /** Application handle, same as {@link RegisteredClassFactory#getHInstance()}. */
@@ -43,6 +45,9 @@ public class RegisteredClass {
     /** Unique Window Class Name */
     public final String getName() { return className; }
 
+    /** Unique associated dispatch thread context for this Window Class, or 0 for none. */
+    public final long getHDispThreadContext() { return hDDTCtx; }
+
     @Override
-    public final String toString() { return "RegisteredClass[handle 0x"+Long.toHexString(hInstance)+", "+className+"]"; }
+    public final String toString() { return "RegisteredClass[handle 0x"+Long.toHexString(hInstance)+", "+className+", dtx 0x"+Long.toHexString(hDDTCtx)+"]"; }
 }
diff --git a/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClassFactory.java b/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClassFactory.java
index 19a48d3bf..ee41fe192 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClassFactory.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/windows/RegisteredClassFactory.java
@@ -49,6 +49,7 @@ public class RegisteredClassFactory {
 
     private final String classBaseName;
     private final long wndProc;
+    private final boolean useDummyDispatchThread;
 
     private RegisteredClass sharedClass = null;
     private int classIter = 0;
@@ -59,24 +60,29 @@ public class RegisteredClassFactory {
 
     @Override
     public final String toString() { return "RegisteredClassFactory[moduleHandle "+toHexString(hInstance)+", "+classBaseName+
-            ", wndProc "+toHexString(wndProc)+", shared[refCount "+sharedRefCount+", class "+sharedClass+"]]"; }
+            ", wndProc "+toHexString(wndProc)+", useDDT "+useDummyDispatchThread+", shared[refCount "+sharedRefCount+", class "+sharedClass+"]]"; }
 
     /**
      * Release the {@link RegisteredClass} of all {@link RegisteredClassFactory}.
      */
     public static void shutdownSharedClasses() {
         synchronized(registeredFactories) {
+            if( DEBUG ) {
+                System.err.println("RegisteredClassFactory.shutdownSharedClasses: "+registeredFactories.size());
+            }
             for(int j=0; j<registeredFactories.size(); j++) {
                 final RegisteredClassFactory rcf = registeredFactories.get(j);
                 synchronized(rcf.sync) {
                     if(null != rcf.sharedClass) {
-                        GDIUtil.DestroyWindowClass(rcf.sharedClass.getHInstance(), rcf.sharedClass.getName());
+                        GDIUtil.DestroyWindowClass0(rcf.sharedClass.getHInstance(), rcf.sharedClass.getName(), rcf.sharedClass.getHDispThreadContext());
                         rcf.sharedClass = null;
                         rcf.sharedRefCount = 0;
                         rcf.classIter = 0;
                         if(DEBUG) {
-                          System.err.println("RegisteredClassFactory #"+j+"/"+registeredFactories.size()+" shutdownSharedClasses : "+rcf.sharedClass);
+                            System.err.println("RegisteredClassFactory #"+j+"/"+registeredFactories.size()+": shutdownSharedClasses : "+rcf.sharedClass);
                         }
+                    } else if(DEBUG) {
+                        System.err.println("RegisteredClassFactory #"+j+"/"+registeredFactories.size()+": null");
                     }
                 }
             }
@@ -86,9 +92,10 @@ public class RegisteredClassFactory {
     /** Application handle. */
     public static long getHInstance() { return hInstance; }
 
-    public RegisteredClassFactory(String classBaseName, long wndProc) {
+    public RegisteredClassFactory(String classBaseName, long wndProc, boolean useDummyDispatchThread) {
         this.classBaseName = classBaseName;
         this.wndProc = wndProc;
+        this.useDummyDispatchThread = useDummyDispatchThread;
         synchronized(registeredFactories) {
             registeredFactories.add(this);
         }
@@ -107,12 +114,21 @@ public class RegisteredClassFactory {
                   // Retry with next clazz name, this could happen if more than one JVM is running
                   clazzName = classBaseName + classIter;
                   classIter++;
-                  registered = GDIUtil.CreateWindowClass(hInstance, clazzName, wndProc);
+                  registered = GDIUtil.CreateWindowClass0(hInstance, clazzName, wndProc);
               }
               if( !registered ) {
                   throw new NativeWindowException("Error: Could not create WindowClass: "+clazzName);
               }
-              sharedClass = new RegisteredClass(hInstance, clazzName);
+              final long hDispatchThread;
+              if( useDummyDispatchThread ) {
+                  hDispatchThread = GDIUtil.CreateDummyDispatchThread0();
+                  if( 0 == hDispatchThread ) {
+                      throw new NativeWindowException("Error: Could not create DDT "+clazzName);
+                  }
+              } else {
+                  hDispatchThread = 0;
+              }
+              sharedClass = new RegisteredClass(hInstance, clazzName, hDispatchThread);
               if(DEBUG) {
                   System.err.println("RegisteredClassFactory getSharedClass ("+sharedRefCount+") initialized: "+sharedClass);
               }
@@ -137,7 +153,7 @@ public class RegisteredClassFactory {
               throw new InternalError("Error ("+sharedRefCount+"): SharedClass is null");
           }
           if( 0 == sharedRefCount ) {
-              GDIUtil.DestroyWindowClass(sharedClass.getHInstance(), sharedClass.getName());
+              GDIUtil.DestroyWindowClass0(sharedClass.getHInstance(), sharedClass.getName(), sharedClass.getHDispThreadContext());
               if(DEBUG) {
                   System.err.println("RegisteredClassFactory releaseSharedClass ("+sharedRefCount+") released: "+sharedClass);
               }
diff --git a/src/nativewindow/native/NativewindowCommon.c b/src/nativewindow/native/NativewindowCommon.c
index e909c0494..212bdf82f 100644
--- a/src/nativewindow/native/NativewindowCommon.c
+++ b/src/nativewindow/native/NativewindowCommon.c
@@ -1,6 +1,7 @@
 
 #include "NativewindowCommon.h"
 #include <string.h>
+#include <sys/time.h>
 
 static const char * const ClazzNameRuntimeException = "java/lang/RuntimeException";
 static jclass    runtimeExceptionClz=NULL;
@@ -106,3 +107,9 @@ JNIEnv* NativewindowCommon_GetJNIEnv (JavaVM * jvmHandle, int jvmVersion, int as
     return curEnv;
 }
 
+int64_t NativewindowCommon_CurrentTimeMillis() {
+    struct timeval tv;
+    gettimeofday(&tv,NULL);
+    return (int64_t)tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
diff --git a/src/nativewindow/native/NativewindowCommon.h b/src/nativewindow/native/NativewindowCommon.h
index a2975f3fd..a23fad9fd 100644
--- a/src/nativewindow/native/NativewindowCommon.h
+++ b/src/nativewindow/native/NativewindowCommon.h
@@ -4,6 +4,7 @@
 
 #include <jni.h>
 #include <stdlib.h>
+#include <gluegen_stdint.h>
 
 int NativewindowCommon_init(JNIEnv *env);
 
@@ -15,4 +16,6 @@ void NativewindowCommon_throwNewRuntimeException(JNIEnv *env, const char* msg, .
 
 JNIEnv* NativewindowCommon_GetJNIEnv (JavaVM * jvmHandle, int jvmVersion, int asDaemon, int * shallBeDetached);
 
+int64_t NativewindowCommon_CurrentTimeMillis();
+
 #endif
diff --git a/src/nativewindow/native/win32/GDImisc.c b/src/nativewindow/native/win32/GDImisc.c
index d3ac3873c..b55988c11 100644
--- a/src/nativewindow/native/win32/GDImisc.c
+++ b/src/nativewindow/native/win32/GDImisc.c
@@ -20,8 +20,10 @@
 
 #ifdef VERBOSE_ON
     #define DBG_PRINT(args...) fprintf(stderr, args);
+    #define DBG_PRINT_FLUSH(args...) fprintf(stderr, args); fflush(stderr);
 #else
     #define DBG_PRINT(args...)
+    #define DBG_PRINT_FLUSH(args...)
 #endif
 
 static const char * const ClazzNamePoint = "javax/media/nativewindow/util/Point";
@@ -30,12 +32,17 @@ static const char * const ClazzNamePointCstrSignature = "(II)V";
 
 static jclass pointClz = NULL;
 static jmethodID pointCstr = NULL;
+static jmethodID dumpStackID = NULL;
 
-static volatile DWORD threadid = 0;
+typedef struct {
+  HANDLE threadHandle;
+  DWORD threadId;
+  volatile BOOL threadReady;
+  volatile BOOL threadDead;
+} DummyThreadContext;
 
-typedef struct ThreadParam_s
-{
-  jlong jHInstance;
+typedef struct {
+  HINSTANCE hInstance;
   const TCHAR* wndClassName;
   const TCHAR* wndName;
   jint x;
@@ -44,17 +51,88 @@ typedef struct ThreadParam_s
   jint height;
   volatile HWND hWnd;
   volatile BOOL threadReady;
-} ThreadParam;
+} DummyThreadCommand;
 
 #define TM_OPENWIN WM_APP+1
 #define TM_CLOSEWIN WM_APP+2
 #define TM_STOP WM_APP+3
 
-DWORD WINAPI ThreadFunc(LPVOID param)
+static const char * sTM_OPENWIN = "TM_OPENWIN";
+static const char * sTM_CLOSEWIN = "TM_CLOSEWIN";
+static const char * sTM_STOP = "TM_STOP";
+
+/**  3s timeout */
+static const int64_t TIME_OUT = 3000000;
+
+static jboolean DDT_CheckAlive(JNIEnv *env, const char *msg, DummyThreadContext *ctx) {
+    if( ctx->threadDead ) {
+        NativewindowCommon_throwNewRuntimeException(env, "DDT is dead at %s", msg);
+        return JNI_FALSE;
+    } else {
+        DBG_PRINT_FLUSH("*** DDT-Check ALIVE @ %s\n", msg);
+        return JNI_TRUE;
+    }
+}
+
+static jboolean DDT_WaitUntilCreated(JNIEnv *env, DummyThreadContext *ctx, BOOL created) {
+    const int64_t t0 = NativewindowCommon_CurrentTimeMillis();
+    int64_t t1 = t0;
+    if( created ) {
+        while( !ctx->threadReady && t1-t0 < TIME_OUT ) {
+            t1 = NativewindowCommon_CurrentTimeMillis();
+        }
+        if( !ctx->threadReady ) {
+            NativewindowCommon_throwNewRuntimeException(env, "TIMEOUT (%d ms) while waiting for DDT CREATED", (int)(t1-t0));
+            return JNI_FALSE;
+        }
+        DBG_PRINT_FLUSH("*** DDT-Check CREATED\n");
+    } else {
+        while( !ctx->threadDead && t1-t0 < TIME_OUT ) {
+            t1 = NativewindowCommon_CurrentTimeMillis();
+        }
+        if( !ctx->threadDead ) {
+            NativewindowCommon_throwNewRuntimeException(env, "TIMEOUT (%d ms) while waiting for DDT DESTROYED", (int)(t1-t0));
+            return JNI_FALSE;
+        }
+        DBG_PRINT_FLUSH("*** DDT-Check DEAD\n");
+    }
+    return JNI_TRUE;
+}
+
+static jboolean DDT_WaitUntilReady(JNIEnv *env, const char *msg, DummyThreadCommand *cmd) {
+    const int64_t t0 = NativewindowCommon_CurrentTimeMillis();
+    int64_t t1 = t0;
+    while( !cmd->threadReady && t1-t0 < TIME_OUT ) {
+        t1 = NativewindowCommon_CurrentTimeMillis();
+    }
+    if( !cmd->threadReady ) {
+        NativewindowCommon_throwNewRuntimeException(env, "TIMEOUT (%d ms) while waiting for DDT %s", (int)(t1-t0), msg);
+        return JNI_FALSE;
+    }
+    DBG_PRINT_FLUSH("*** DDT-Check READY @ %s\n", msg);
+    return JNI_TRUE;
+}
+
+static HWND DummyWindowCreate
+    (HINSTANCE hInstance, const TCHAR* wndClassName, const TCHAR* wndName, jint x, jint y, jint width, jint height) 
+{
+    DWORD dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
+    DWORD dwStyle = WS_OVERLAPPEDWINDOW;
+    HWND hWnd = CreateWindowEx( dwExStyle,
+                                wndClassName,
+                                wndName,
+                                dwStyle | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
+                                x, y, width, height,
+                                NULL, NULL, hInstance, NULL );
+    return hWnd;
+}
+
+static DWORD WINAPI DummyDispatchThreadFunc(LPVOID param)
 {
     MSG msg;
     BOOL bRet;
-    ThreadParam *startupThreadParam = (ThreadParam*)param;
+    BOOL bEOL=FALSE;
+    DummyThreadContext *threadContext = (DummyThreadContext*)param;
 
     /* there can not be any messages for us now, as the creator waits for
        threadReady before continuing, but we must use this PeekMessage() to
@@ -62,42 +140,40 @@ DWORD WINAPI ThreadFunc(LPVOID param)
     PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE);
 
     /* now we can safely say: we have a qeue and are ready to receive messages */
-    startupThreadParam->threadReady = TRUE;
-
-    while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0) {
-        if (bRet == -1) {
-            return 0;
+    // threadContext->threadId = GetCurrentThreadId();
+    threadContext->threadDead = FALSE;
+    threadContext->threadReady = TRUE;
+
+    while( !bEOL && (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0 ) {
+        if ( -1 == bRet ) {
+            fprintf(stderr, "DummyDispatchThread (id %d): GetMessage Error %d, werr %d\n", 
+                (int)threadContext->threadId, (int)bRet, (int)GetLastError());
+            fflush(stderr);
+            bEOL = TRUE;
+            break; // EOL
         } else {
             switch(msg.message) {
                 case TM_OPENWIN: {
-                    ThreadParam *tParam = (ThreadParam*)msg.wParam;
-                    HINSTANCE hInstance = (HINSTANCE) (intptr_t) tParam->jHInstance;
-                    DWORD dwExStyle;
-                    DWORD dwStyle;
-        
-                    dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
-                    dwStyle = WS_OVERLAPPEDWINDOW;
-        
-                    HWND hwnd = CreateWindowEx( dwExStyle,
-                                    tParam->wndClassName,
-                                    tParam->wndName,
-                                    dwStyle | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
-                                    tParam->x, tParam->y, tParam->width, tParam->height,
-                                    NULL, NULL, hInstance, NULL );
-        
-                    tParam->hWnd = hwnd;
+                    DummyThreadCommand *tParam = (DummyThreadCommand*)msg.wParam;
+                    DBG_PRINT_FLUSH("*** DDT-Dispatch OPENWIN\n");
+                    tParam->hWnd = DummyWindowCreate(tParam->hInstance, tParam->wndClassName, tParam->wndName, tParam->x, tParam->y, tParam->width, tParam->height);
                     tParam->threadReady = TRUE;
                   }
                   break;
                 case TM_CLOSEWIN: {
-                    ThreadParam *tParam = (ThreadParam*)msg.wParam;
-                    HWND hwnd = tParam->hWnd;
-                    DestroyWindow(hwnd);
+                    DummyThreadCommand *tParam = (DummyThreadCommand*)msg.wParam;
+                    DBG_PRINT_FLUSH("*** DDT-Dispatch CLOSEWIN\n");
+                    DestroyWindow(tParam->hWnd);
                     tParam->threadReady = TRUE;
                   }
                   break;
-                case TM_STOP:
-                  return 0;
+                case TM_STOP: {
+                    DummyThreadCommand *tParam = (DummyThreadCommand*)msg.wParam;
+                    DBG_PRINT_FLUSH("*** DDT-Dispatch STOP -> DEAD\n");
+                    tParam->threadReady = TRUE;
+                    bEOL = TRUE;
+                  }
+                  break; // EOL
                 default:
                   TranslateMessage(&msg); 
                   DispatchMessage(&msg); 
@@ -105,8 +181,12 @@ DWORD WINAPI ThreadFunc(LPVOID param)
             }
         }
     }
+    /* dead */
+    DBG_PRINT_FLUSH("*** DDT-Dispatch DEAD\n");
+    threadContext->threadDead = TRUE;
+    ExitThread(0);
     return 0;
-} /* ThreadFunc */
+}
 
 
 HINSTANCE GetApplicationHandle() {
@@ -115,11 +195,48 @@ HINSTANCE GetApplicationHandle() {
 
 /*   Java->C glue code:
  *   Java package: jogamp.nativewindow.windows.GDIUtil
- *    Java method: boolean CreateWindowClass(long hInstance, java.lang.String clazzName, long wndProc)
- *     C function: BOOL CreateWindowClass(HANDLE hInstance, LPCSTR clazzName, HANDLE wndProc);
+ *   Java method: long CreateDummyDispatchThread0()
+ */
+JNIEXPORT jlong JNICALL
+Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyDispatchThread0
+    (JNIEnv *env, jclass _unused)
+{
+    DWORD threadId = 0;
+    DummyThreadContext * dispThreadCtx = calloc(1, sizeof(DummyThreadContext));
+
+    dispThreadCtx->threadHandle = CreateThread(NULL, 0, DummyDispatchThreadFunc, (LPVOID)dispThreadCtx, 0, &threadId);
+    if( NULL == dispThreadCtx->threadHandle || 0 == threadId ) {
+        const HANDLE threadHandle = dispThreadCtx->threadHandle;
+        if( NULL != threadHandle ) {
+            TerminateThread(threadHandle, 0);
+        }
+        free(dispThreadCtx);
+        NativewindowCommon_throwNewRuntimeException(env, "DDT CREATE failed handle %p, id %d, werr %d", 
+            (void*)threadHandle, (int)threadId, (int)GetLastError());
+        return (jlong)0;
+    }
+    if( JNI_FALSE == DDT_WaitUntilCreated(env, dispThreadCtx, TRUE) ) {
+        const HANDLE threadHandle = dispThreadCtx->threadHandle;
+        if( NULL != threadHandle ) {
+            TerminateThread(threadHandle, 0);
+        }
+        free(dispThreadCtx);
+        NativewindowCommon_throwNewRuntimeException(env, "DDT CREATE (ack) failed handle %p, id %d, werr %d", 
+            (void*)threadHandle, (int)threadId, (int)GetLastError());
+        return (jlong)0;
+    }
+    DBG_PRINT_FLUSH("*** DDT Created %d\n", (int)threadId);
+    dispThreadCtx->threadId = threadId;
+    return (jlong) (intptr_t) dispThreadCtx;
+}
+
+/*   Java->C glue code:
+ *   Java package: jogamp.nativewindow.windows.GDIUtil
+ *    Java method: boolean CreateWindowClass0(long hInstance, java.lang.String clazzName, long wndProc)
+ *     C function: BOOL CreateWindowClass0(HANDLE hInstance, LPCSTR clazzName, HANDLE wndProc);
  */
 JNIEXPORT jboolean JNICALL
-Java_jogamp_nativewindow_windows_GDIUtil_CreateWindowClass
+Java_jogamp_nativewindow_windows_GDIUtil_CreateWindowClass0
     (JNIEnv *env, jclass _unused, jlong jHInstance, jstring jClazzName, jlong wndProc)
 {
     HINSTANCE hInstance = (HINSTANCE) (intptr_t) jHInstance;
@@ -127,11 +244,6 @@ Java_jogamp_nativewindow_windows_GDIUtil_CreateWindowClass
     WNDCLASS  wc;
     jboolean res;
 
-    if( 0 != threadid ) {
-        NativewindowCommon_throwNewRuntimeException(env, "Native threadid already created 0x%X", (int)threadid);
-        return JNI_FALSE;
-    }
-
 #ifdef UNICODE
     clazzName = NewtCommon_GetNullTerminatedStringChars(env, jClazzName);
 #else
@@ -164,31 +276,20 @@ Java_jogamp_nativewindow_windows_GDIUtil_CreateWindowClass
     (*env)->ReleaseStringUTFChars(env, jClazzName, clazzName);
 #endif
 
-    if( JNI_TRUE == res ) {
-        ThreadParam tParam = {0};
-
-        CreateThread(NULL, 0, ThreadFunc, (LPVOID)&tParam, 0, (DWORD *)&threadid);
-        if(threadid) {
-            while(!tParam.threadReady) { /* nop */ }
-        } else {
-            res = JNI_FALSE;
-        }
-    }
-
     return res;
 }
 
 /*   Java->C glue code:
  *   Java package: jogamp.nativewindow.windows.GDIUtil
- *    Java method: boolean DestroyWindowClass(long hInstance, java.lang.String className)
- *     C function: BOOL DestroyWindowClass(HANDLE hInstance, LPCSTR className);
+ *   Java method: boolean DestroyWindowClass0(long hInstance, java.lang.String className, long dispThreadCtx)
  */
 JNIEXPORT jboolean JNICALL
-Java_jogamp_nativewindow_windows_GDIUtil_DestroyWindowClass
-    (JNIEnv *env, jclass _unused, jlong jHInstance, jstring jClazzName) 
+Java_jogamp_nativewindow_windows_GDIUtil_DestroyWindowClass0
+    (JNIEnv *env, jclass gdiClazz, jlong jHInstance, jstring jClazzName, jlong jDispThreadCtx) 
 {
     HINSTANCE hInstance = (HINSTANCE) (intptr_t) jHInstance;
     const TCHAR* clazzName = NULL;
+    DummyThreadContext * dispThreadCtx = (DummyThreadContext *) (intptr_t) jDispThreadCtx;
     jboolean res;
 
 #ifdef UNICODE
@@ -205,39 +306,73 @@ Java_jogamp_nativewindow_windows_GDIUtil_DestroyWindowClass
     (*env)->ReleaseStringUTFChars(env, jClazzName, clazzName);
 #endif
 
-    if( 0 == threadid ) {
-        NativewindowCommon_throwNewRuntimeException(env, "Native threadid zero 0x%X", (int)threadid);
-        return JNI_FALSE;
-    }
+    if( NULL != dispThreadCtx) {
+        const HANDLE threadHandle = dispThreadCtx->threadHandle;
+        const DWORD threadId = dispThreadCtx->threadId;
+        DummyThreadCommand tParam = {0};
+        tParam.threadReady = FALSE;
+        DBG_PRINT_FLUSH("*** DDT Destroy %d\n", (int)threadId);
+#ifdef VERBOSE_ON
+        (*env)->CallStaticVoidMethod(env, gdiClazz, dumpStackID);
+#endif
 
-    PostThreadMessage(threadid, TM_STOP, 0, 0);
+        if( JNI_FALSE == DDT_CheckAlive(env, sTM_STOP, dispThreadCtx) ) {
+            free(dispThreadCtx);
+            NativewindowCommon_throwNewRuntimeException(env, "DDT %s (alive) failed handle %p, id %d, werr %d", 
+                sTM_STOP, (void*)threadHandle, (int)threadId, (int)GetLastError());
+            return JNI_FALSE;
+        }
+        if ( 0 != PostThreadMessage(dispThreadCtx->threadId, TM_STOP, (WPARAM)&tParam, 0) ) {
+            if( JNI_FALSE == DDT_WaitUntilReady(env, sTM_STOP, &tParam) ) {
+                if( NULL != threadHandle ) {
+                    TerminateThread(threadHandle, 0);
+                }
+                free(dispThreadCtx);
+                NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s (ack) failed handle %p, id %d, werr %d",
+                    sTM_STOP, (void*)threadHandle, (int)threadId, (int)GetLastError());
+                return JNI_FALSE;
+            }
+            if( JNI_FALSE == DDT_WaitUntilCreated(env, dispThreadCtx, FALSE) ) {
+                if( NULL != threadHandle ) {
+                    TerminateThread(threadHandle, 0);
+                }
+                free(dispThreadCtx);
+                NativewindowCommon_throwNewRuntimeException(env, "DDT KILL %s (ack) failed handle %p, id %d, werr %d",
+                    sTM_STOP, (void*)threadHandle, (int)threadId, (int)GetLastError());
+                return JNI_FALSE;
+            }
+            free(dispThreadCtx); // free after proper DDT shutdown!
+        } else {
+            if( NULL != threadHandle ) {
+                TerminateThread(threadHandle, 0);
+            }
+            free(dispThreadCtx);
+            NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s failed handle %p, id %d, werr %d",
+                sTM_STOP, (void*)threadHandle, (int)threadId, (int)GetLastError());
+            return JNI_FALSE;
+        }
+    }
 
     return res;
 }
 
 /*   Java->C glue code:
  *   Java package: jogamp.nativewindow.windows.GDIUtil
- *    Java method: long CreateDummyWindowAndMessageLoop(long hInstance, java.lang.String className, java.lang.String windowName, int x, int y, int width, int height)
- *     C function: HANDLE CreateDummyWindowAndMessageLoop(HANDLE hInstance, LPCSTR className, LPCSTR windowName, int x, int y, int width, int height);
+ *   Java method: long CreateDummyWindow0(long hInstance, java.lang.String className, jlong dispThreadCtx, java.lang.String windowName, int x, int y, int width, int height)
  */
 JNIEXPORT jlong JNICALL
-Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyWindowAndMessageLoop
-    (JNIEnv *env, jclass _unused, jlong jHInstance, jstring jWndClassName, jstring jWndName, jint x, jint y, jint width, jint height) 
+Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyWindow0
+    (JNIEnv *env, jclass _unused, jlong jHInstance, jstring jWndClassName, jlong jDispThreadCtx, jstring jWndName, jint x, jint y, jint width, jint height) 
 {
-    volatile HWND hWnd = 0;
-    ThreadParam tParam = {0};
-
-    if( 0 == threadid ) {
-        NativewindowCommon_throwNewRuntimeException(env, "Native threadid zero 0x%X", (int)threadid);
-        return JNI_FALSE;
-    }
+    DummyThreadContext * dispThreadCtx = (DummyThreadContext *) (intptr_t) jDispThreadCtx;
+    DummyThreadCommand tParam = {0};
 
-    tParam.jHInstance = jHInstance;
+    tParam.hInstance = (HINSTANCE) (intptr_t) jHInstance;
     tParam.x = x;
     tParam.y = y;
     tParam.width = width;
     tParam.height = height;
-    tParam.hWnd = hWnd;
+    tParam.hWnd = 0;
     tParam.threadReady = FALSE;
 
 #ifdef UNICODE
@@ -248,9 +383,37 @@ Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyWindowAndMessageLoop
     tParam.wndName = (*env)->GetStringUTFChars(env, jWndName, NULL);
 #endif
 
-    PostThreadMessage(threadid, TM_OPENWIN, (WPARAM)&tParam, 0);
-
-    while(!tParam.threadReady) { /* nop */ }
+    if( NULL == dispThreadCtx ) {
+        tParam.hWnd = DummyWindowCreate(tParam.hInstance, tParam.wndClassName, tParam.wndName, tParam.x, tParam.y, tParam.width, tParam.height);
+    } else {
+        const HANDLE threadHandle = dispThreadCtx->threadHandle;
+        const DWORD threadId = dispThreadCtx->threadId;
+        if( JNI_FALSE == DDT_CheckAlive(env, sTM_OPENWIN, dispThreadCtx) ) {
+            free(dispThreadCtx);
+            NativewindowCommon_throwNewRuntimeException(env, "DDT %s (alive) failed handle %p, id %d, werr %d", 
+                sTM_OPENWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+        } else {
+            if( 0 != PostThreadMessage(dispThreadCtx->threadId, TM_OPENWIN, (WPARAM)&tParam, 0) ) {
+                if( JNI_FALSE == DDT_WaitUntilReady(env, sTM_OPENWIN, &tParam) ) {
+                    if( NULL != threadHandle ) {
+                        TerminateThread(threadHandle, 0);
+                    }
+                    free(dispThreadCtx);
+                    tParam.hWnd = 0;
+                    NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s (ack) failed handle %p, id %d, werr %d", 
+                        sTM_OPENWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+                }
+            } else {
+                if( NULL != threadHandle ) {
+                    TerminateThread(threadHandle, 0);
+                }
+                free(dispThreadCtx);
+                tParam.hWnd = 0;
+                NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s to handle %p, id %d failed, werr %d", 
+                    sTM_OPENWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+            }
+        }
+    }
 
 #ifdef UNICODE
     free((void*) tParam.wndClassName);
@@ -260,62 +423,66 @@ Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyWindowAndMessageLoop
     (*env)->ReleaseStringUTFChars(env, jWndName, tParam.wndName);
 #endif
 
-    return (jlong) (intptr_t) hWnd;
+    return (jlong) (intptr_t) tParam.hWnd;
 }
 
-/*   Java->C glue code:
- *   Java package: jogamp.nativewindow.windows.GDIUtil
- *    Java method: long CreateDummyWindow0(long hInstance, java.lang.String className, java.lang.String windowName, int x, int y, int width, int height)
- *     C function: HANDLE CreateDummyWindow0(HANDLE hInstance, LPCSTR className, LPCSTR windowName, int x, int y, int width, int height);
+/*
+ * Class:     jogamp_nativewindow_windows_GDIUtil
+ * Method:    DestroyWindow0
  */
-JNIEXPORT jlong JNICALL
-Java_jogamp_nativewindow_windows_GDIUtil_CreateDummyWindow0
-    (JNIEnv *env, jclass _unused, jlong jHInstance, jstring jWndClassName, jstring jWndName, jint x, jint y, jint width, jint height) 
+JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_DestroyWindow0
+(JNIEnv *env, jclass unused, jlong jDispThreadCtx, jlong jwin)
 {
-    HINSTANCE hInstance = (HINSTANCE) (intptr_t) jHInstance;
-    const TCHAR* wndClassName = NULL;
-    const TCHAR* wndName = NULL;
-    DWORD     dwExStyle;
-    DWORD     dwStyle;
-    HWND      hWnd;
-
-#ifdef UNICODE
-    wndClassName = NewtCommon_GetNullTerminatedStringChars(env, jWndClassName);
-    wndName = NewtCommon_GetNullTerminatedStringChars(env, jWndName);
-#else
-    wndClassName = (*env)->GetStringUTFChars(env, jWndClassName, NULL);
-    wndName = (*env)->GetStringUTFChars(env, jWndName, NULL);
-#endif
-
-    dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
-    dwStyle = WS_OVERLAPPEDWINDOW;
-
-    hWnd = CreateWindowEx( dwExStyle,
-                           wndClassName,
-                           wndName,
-                           dwStyle | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
-                           x, y, width, height,
-                           NULL, NULL, hInstance, NULL );
+    jboolean res = JNI_TRUE;
+    DummyThreadContext * dispThreadCtx = (DummyThreadContext *) (intptr_t) jDispThreadCtx;
+    HWND hWnd = (HWND) (intptr_t) jwin;
+    if( NULL == dispThreadCtx ) {
+        DestroyWindow(hWnd);
+    } else {
+        const HANDLE threadHandle = dispThreadCtx->threadHandle;
+        const DWORD threadId = dispThreadCtx->threadId;
+        DummyThreadCommand tParam = {0};
 
-#ifdef UNICODE
-    free((void*) wndClassName);
-    free((void*) wndName);
-#else
-    (*env)->ReleaseStringUTFChars(env, jWndClassName, wndClassName);
-    (*env)->ReleaseStringUTFChars(env, jWndName, wndName);
-#endif
+        tParam.hWnd = hWnd;
+        tParam.threadReady = FALSE;
 
-    return (jlong) (intptr_t) hWnd;
+        if( JNI_FALSE == DDT_CheckAlive(env, sTM_CLOSEWIN, dispThreadCtx) ) {
+            free(dispThreadCtx);
+            res = JNI_FALSE;
+            NativewindowCommon_throwNewRuntimeException(env, "DDT %s (alive) failed handle %p, id %d, werr %d", 
+                sTM_CLOSEWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+        } else {
+            if ( 0 != PostThreadMessage(dispThreadCtx->threadId, TM_CLOSEWIN, (WPARAM)&tParam, 0) ) {
+                if( JNI_FALSE == DDT_WaitUntilReady(env, sTM_CLOSEWIN, &tParam) ) {
+                    if( NULL != threadHandle ) {
+                        TerminateThread(threadHandle, 0);
+                    }
+                    free(dispThreadCtx);
+                    res = JNI_FALSE;
+                    NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s (ack) failed handle %p, id %d, werr %d", 
+                        sTM_CLOSEWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+                }
+            } else {
+                if( NULL != threadHandle ) {
+                    TerminateThread(threadHandle, 0);
+                }
+                free(dispThreadCtx);
+                res = JNI_FALSE;
+                NativewindowCommon_throwNewRuntimeException(env, "DDT Post %s to handle %p, id %d failed, werr %d", 
+                    sTM_CLOSEWIN, (void*)threadHandle, (int)threadId, (int)GetLastError());
+            }
+        }
+    }
+    return res;
 }
 
-
 /*
  * Class:     jogamp_nativewindow_windows_GDIUtil
  * Method:    initIDs0
  * Signature: ()Z
  */
 JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_initIDs0
-  (JNIEnv *env, jclass clazz)
+  (JNIEnv *env, jclass gdiClazz)
 {
     if(NativewindowCommon_init(env)) {
         jclass c = (*env)->FindClass(env, ClazzNamePoint);
@@ -332,11 +499,15 @@ JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_initIDs0
             NativewindowCommon_FatalError(env, "FatalError jogamp_nativewindow_windows_GDIUtil: can't fetch %s.%s %s",
                 ClazzNamePoint, ClazzAnyCstrName, ClazzNamePointCstrSignature);
         }
+        dumpStackID = (*env)->GetStaticMethodID(env, gdiClazz, "dumpStack", "()V");
+        if(NULL==dumpStackID) {
+            NativewindowCommon_FatalError(env, "FatalError jogamp_nativewindow_windows_GDIUtil: can't get method dumpStack");
+        }
     }
     return JNI_TRUE;
 }
 
-LRESULT CALLBACK DummyWndProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
+static LRESULT CALLBACK DummyWndProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
     return DefWindowProc(hWnd,uMsg,wParam,lParam);
 }
 
@@ -379,8 +550,8 @@ JNIEXPORT jobject JNICALL Java_jogamp_nativewindow_windows_GDIUtil_GetRelativeLo
 JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_IsChild0
   (JNIEnv *env, jclass unused, jlong jwin)
 {
-    HWND hwnd = (HWND) (intptr_t) jwin;
-    LONG style = GetWindowLong(hwnd, GWL_STYLE);
+    HWND hWnd = (HWND) (intptr_t) jwin;
+    LONG style = GetWindowLong(hWnd, GWL_STYLE);
     BOOL bIsChild = 0 != (style & WS_CHILD) ;
     return bIsChild ? JNI_TRUE : JNI_FALSE;
 }
@@ -392,34 +563,9 @@ JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_IsChild0
 JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_IsUndecorated0
   (JNIEnv *env, jclass unused, jlong jwin)
 {
-    HWND hwnd = (HWND) (intptr_t) jwin;
-    LONG style = GetWindowLong(hwnd, GWL_STYLE);
+    HWND hWnd = (HWND) (intptr_t) jwin;
+    LONG style = GetWindowLong(hWnd, GWL_STYLE);
     BOOL bIsUndecorated = 0 != (style & (WS_CHILD|WS_POPUP)) ;
     return bIsUndecorated ? JNI_TRUE : JNI_FALSE;
 }
 
-/*
- * Class:     jogamp_nativewindow_windows_GDIUtil
- * Method:    SendCloseMessage
- */
-JNIEXPORT jboolean JNICALL Java_jogamp_nativewindow_windows_GDIUtil_SendCloseMessage
-(JNIEnv *env, jclass unused, jlong jwin)
-{
-    ThreadParam tParam = {0};
-    volatile HWND hwnd = (HWND) (intptr_t) jwin;
-
-    if( 0 == threadid ) {
-        NativewindowCommon_throwNewRuntimeException(env, "Native threadid zero 0x%X", (int)threadid);
-        return JNI_FALSE;
-    }
-
-    tParam.hWnd = hwnd;
-    tParam.threadReady = FALSE;
-
-    PostThreadMessage(threadid, TM_CLOSEWIN, (WPARAM)&tParam, 0);
-
-    while(!tParam.threadReady) { /* nop */ }
-
-    return JNI_TRUE;
-}
-
diff --git a/src/newt/classes/jogamp/newt/driver/windows/DisplayDriver.java b/src/newt/classes/jogamp/newt/driver/windows/DisplayDriver.java
index d8ff7ecb5..c4cfd98b3 100644
--- a/src/newt/classes/jogamp/newt/driver/windows/DisplayDriver.java
+++ b/src/newt/classes/jogamp/newt/driver/windows/DisplayDriver.java
@@ -51,7 +51,7 @@ public class DisplayDriver extends DisplayImpl {
     static {
         NEWTJNILibLoader.loadNEWT();
 
-        sharedClassFactory = new RegisteredClassFactory(newtClassBaseName, WindowDriver.getNewtWndProc0());
+        sharedClassFactory = new RegisteredClassFactory(newtClassBaseName, WindowDriver.getNewtWndProc0(), false /* useDummyDispatchThread */);
 
         if (!WindowDriver.initIDs0(RegisteredClassFactory.getHInstance())) {
             throw new NativeWindowException("Failed to initialize WindowsWindow jmethodIDs");