display(...)

        this.gl.glBindFramebuffer(GL_FRAMEBUFFER, this.frameBuffer); //The framebuffer was successfully set up and no errors happened

        this.gl.glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        callback.render(this);  //In this case, the callback causes a single call to renderSprite(...,32,32)
                    //Though nothing gets rendered into the texture
        this.gl.glBindFramebuffer(GL_FRAMEBUFFER, 0);

        this.gl.glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        //Create a new Sprite that represents the texture that was just rendered to
        Texture t = new Texture(renderedTexture, ww, wh, ww, wh);
        Sprite s = new Sprite(t);
        //
        this.renderSprite(s, 64, 32);
        callback.render(this); //this time we render directly to the screen, and everything works fine ...