It’s simple:

1. require “glapp”
2. Include GLApp
3. Override as many of the callbacks as you need:

• setup
• update(seconds)
• draw
• keyboard_down(key, modifiers)
• keyboard_up(key, modifiers)
• special_keyboard_down(key, modifiers)
• special_keyboard_up(key, modifiers)
• mouse_click(button, state, x, y)
• mouse_dragging_motion(x, y)
• mouse_passive_motion(x, y)
• If you need more control, override the default behavior of these:

• setup_context
• pre_draw
• post_draw
• resize
• Call show with width, height, title, and whether to be full-screen

Look at the scripts in the examples/ directory.
In fact, here’s one: