numBackBuffers = newNumBackBuffers;
                Win32GraphicsConfig gc =
                        (Win32GraphicsConfig)getGraphicsConfiguration();
                ScreenUpdateManager mgr = ScreenUpdateManager.getInstance();
                oldData = surfaceData;
                mgr.dropScreenSurface(oldData);
                surfaceData =
                    mgr.createScreenSurface(gc, this, numBackBuffers, true);
                if (oldData != null) {
                    oldData.invalidate();
                }