blitString is from glfront package that comes Bones. Here is my rendering part:
frameBuffer.clear(back);
skybox.render(world, frameBuffer); // render the skybox
flower.warning(frameBuffer, displayLevel);
displayLevel.blitString(frameBuffer, "-", frameBuffer.getWidth()-30, 50, 10, null);
displayLevel.blitString(frameBuffer, "+", frameBuffer.getWidth()-30, 150, 10, null);
frameBuffer.blit(trophy, 0, 0, 15, 30, 32, 32, true);
world.renderScene(frameBuffer);
world.draw(frameBuffer);
frameBuffer.display();