+ Window *win2 = new Window;
+ win2->set_title("title2");
+ win2->move(150, 10);
+ win2->resize(200, 300);
+ win2->set_display_callback(display);
+ win2->set_keyboard_callback(keyboard);
+ win2->set_mouse_button_callback(button);
+ win2->set_mouse_motion_callback(motion);
+