Thanks for asking, the backend is built on Ruby on Rails, and we use spinejs as frontend MVC framework, and obviously, bootstrap and jquery is indispensable, the rest are our dirty code, and also we use coffeescript, i think it save much of time for us instead of writing js directly.
thanks for your appreciation and feedback, I think there must be a way to prevent dragging selecting, i've added it to todo, and will implement it soon.