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();
}