 		// calculate delta time
 		float delta = (float)(glfwGetTime() - time);
 		time = glfwGetTime();
+
+		// show FPS in title bar
+		if ((int)time > sec)
+		{
+			sec = (int)time;
+			ostringstream oss;
+			oss << title << " (FPS: " << (int)(1.0f / delta) << ")";
+			glfwSetWindowTitle(window, oss.str().c_str());
+		}
 
 		// update process
 		update(delta);


	// main loop
	double time = glfwGetTime();
	while (!glfwWindowShouldClose(window))
	{
		// update viewport


	// make context current
	glfwMakeContextCurrent(window);

	// turn off vsync
	glfwSwapInterval(0);
}

Application::~Application(void)
