src/macosx/classes/sun/lwawt/macosx/CPlatformEmbeddedFrame.java

@@ -115,11 +115,11 @@
     @Override
     public Image createBackBuffer() {
         Rectangle r = peer.getBounds();
         Image im = null;
         if (!r.isEmpty()) {
-            int transparency = (peer.isOpaque() ? Transparency.OPAQUE : Transparency.TRANSLUCENT);
+            int transparency = peer.isTranslucent() ? Transparency.TRANSLUCENT : Transparency.OPAQUE;
             im = peer.getGraphicsConfiguration().createCompatibleImage(r.width, r.height, transparency);
         }
         return im;
     }