3 files changed, 9 insertions, 7 deletions
diff --git a/src/newt/classes/jogamp/newt/WindowImpl.java b/src/newt/classes/jogamp/newt/WindowImpl.java
index 34f248121..45745e89c 100644
--- a/src/newt/classes/jogamp/newt/WindowImpl.java
+++ b/src/newt/classes/jogamp/newt/WindowImpl.java
@@ -563,7 +563,7 @@ public abstract class WindowImpl implements Window, NEWTEventConsumer
     //
 
     @Override
-    public final int lockSurface() {
+    public final int lockSurface() throws NativeWindowException, RuntimeException {
         windowLock.lock();
         surfaceLock.lock();
         int res = surfaceLock.getHoldCount() == 1 ? LOCK_SURFACE_NOT_READY : LOCK_SUCCESS; // new lock ?
diff --git a/src/newt/classes/jogamp/newt/driver/macosx/MacWindow.java b/src/newt/classes/jogamp/newt/driver/macosx/MacWindow.java
index b45c60e69..942994c13 100644
--- a/src/newt/classes/jogamp/newt/driver/macosx/MacWindow.java
+++ b/src/newt/classes/jogamp/newt/driver/macosx/MacWindow.java
@@ -104,7 +104,10 @@ public class MacWindow extends WindowImpl implements SurfaceChangeable, DriverCl
     @Override
     protected void unlockSurfaceImpl() {
         if(!isOffscreenInstance) {
-            unlockSurface0(getWindowHandle());
+            final long h = getWindowHandle();
+            if(0 != h) {
+                unlockSurface0(h);
+            }
         }
     }
     
diff --git a/src/newt/classes/jogamp/newt/driver/windows/WindowsWindow.java b/src/newt/classes/jogamp/newt/driver/windows/WindowsWindow.java
index a30aa133c..5e636d982 100644
--- a/src/newt/classes/jogamp/newt/driver/windows/WindowsWindow.java
+++ b/src/newt/classes/jogamp/newt/driver/windows/WindowsWindow.java
@@ -87,12 +87,11 @@ public class WindowsWindow extends WindowImpl {
 
     @Override
     protected void unlockSurfaceImpl() {
-        if (0 == hdc) {
-            throw new InternalError("surface not acquired");
+        if (0 != hdc) {
+            GDI.ReleaseDC(getWindowHandle(), hdc);
+            hdc_old = hdc;
+            hdc=0;
         }
-        GDI.ReleaseDC(getWindowHandle(), hdc);
-        hdc_old = hdc;
-        hdc=0;
     }
 
     @Override