4 files changed, 15 insertions, 12 deletions
diff --git a/src/nativewindow/classes/com/jogamp/nativewindow/awt/JAWTWindow.java b/src/nativewindow/classes/com/jogamp/nativewindow/awt/JAWTWindow.java
index 3437358de..3815189ef 100644
--- a/src/nativewindow/classes/com/jogamp/nativewindow/awt/JAWTWindow.java
+++ b/src/nativewindow/classes/com/jogamp/nativewindow/awt/JAWTWindow.java
@@ -278,7 +278,7 @@ public abstract class JAWTWindow implements NativeWindow, OffscreenLayerSurface,
   }
 
   @Override
-  public final int lockSurface() throws NativeWindowException {
+  public final int lockSurface() throws NativeWindowException, RuntimeException  {
     surfaceLock.lock();
     int res = surfaceLock.getHoldCount() == 1 ? LOCK_SURFACE_NOT_READY : LOCK_SUCCESS; // new lock ?
 
@@ -322,7 +322,9 @@ public abstract class JAWTWindow implements NativeWindow, OffscreenLayerSurface,
     if (surfaceLock.getHoldCount() == 1) {
         final AbstractGraphicsDevice adevice = getGraphicsConfiguration().getScreen().getDevice();
         try {
-            unlockSurfaceImpl();
+            if(null != jawt) {
+                unlockSurfaceImpl();
+            }
         } finally {
             adevice.unlock();
         }
diff --git a/src/nativewindow/classes/javax/media/nativewindow/NativeSurface.java b/src/nativewindow/classes/javax/media/nativewindow/NativeSurface.java
index c58b34b18..cec7d4ec3 100644
--- a/src/nativewindow/classes/javax/media/nativewindow/NativeSurface.java
+++ b/src/nativewindow/classes/javax/media/nativewindow/NativeSurface.java
@@ -83,10 +83,11 @@ public interface NativeSurface extends SurfaceUpdatedListener {
    * @return {@link #LOCK_SUCCESS}, {@link #LOCK_SURFACE_CHANGED} or {@link #LOCK_SURFACE_NOT_READY}.
    *
    * @throws RuntimeException after timeout when waiting for the surface lock
+   * @throws NativeWindowException if native locking failed, maybe platform related
    *
    * @see com.jogamp.common.util.locks.RecursiveLock
    */
-  public int lockSurface();
+  public int lockSurface() throws NativeWindowException, RuntimeException;
 
   /**
    * Unlock the surface of this native window
@@ -96,12 +97,13 @@ public interface NativeSurface extends SurfaceUpdatedListener {
    * The implementation shall also invoke {@link AbstractGraphicsDevice#unlock()}
    * for the final unlock (recursive count zero).<P>
    *
-   * @throws RuntimeException if surface is not locked
+   * The implementation shall be fail safe, i.e. tolerant in case the native resources
+   * are already released / unlocked. In this case the implementation shall simply ignore the call.
    *
    * @see #lockSurface
    * @see com.jogamp.common.util.locks.RecursiveLock
    */
-  public void unlockSurface() throws NativeWindowException ;
+  public void unlockSurface();
 
   /**
    * Query if surface is locked by another thread, i.e. not the current one.
diff --git a/src/nativewindow/classes/javax/media/nativewindow/ProxySurface.java b/src/nativewindow/classes/javax/media/nativewindow/ProxySurface.java
index c8cd78d82..1dabc3dcd 100644
--- a/src/nativewindow/classes/javax/media/nativewindow/ProxySurface.java
+++ b/src/nativewindow/classes/javax/media/nativewindow/ProxySurface.java
@@ -123,7 +123,7 @@ public abstract class ProxySurface implements NativeSurface {
     }
 
     @Override
-    public int lockSurface() throws NativeWindowException {
+    public int lockSurface() throws NativeWindowException, RuntimeException  {
         surfaceLock.lock();
         int res = surfaceLock.getHoldCount() == 1 ? LOCK_SURFACE_NOT_READY : LOCK_SUCCESS; // new lock ?
 
diff --git a/src/nativewindow/classes/jogamp/nativewindow/windows/GDISurface.java b/src/nativewindow/classes/jogamp/nativewindow/windows/GDISurface.java
index 4da48bdae..c24f64b32 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/windows/GDISurface.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/windows/GDISurface.java
@@ -74,13 +74,12 @@ public class GDISurface extends ProxySurface {
 
   @Override
   final protected void unlockSurfaceImpl() {
-    if (0 == surfaceHandle) {
-        throw new InternalError("surface not acquired: "+this+", thread: "+Thread.currentThread().getName());
-    }
-    if(0 == GDI.ReleaseDC(windowHandle, surfaceHandle)) {
-        throw new NativeWindowException("DC not released: "+this+", isWindow "+GDI.IsWindow(windowHandle)+", werr "+GDI.GetLastError()+", thread: "+Thread.currentThread().getName());        
+    if (0 != surfaceHandle) {
+        if(0 == GDI.ReleaseDC(windowHandle, surfaceHandle)) {
+            throw new NativeWindowException("DC not released: "+this+", isWindow "+GDI.IsWindow(windowHandle)+", werr "+GDI.GetLastError()+", thread: "+Thread.currentThread().getName());        
+        }
+        surfaceHandle=0;
     }
-    surfaceHandle=0;
   }
 
   @Override