void (ID buttObj, @Nullable Icon arrow) { final BufferedImage img = _getImg4ByteRGBA(arrow); final Pointer raster4ByteRGBA = _getRaster(img); final int w = _getImgW(img); final int h = _getImgH(img); nstLibrary.setArrowImage(buttObj, raster4ByteRGBA, w, h); // creates autorelease-pool internally }