Library for drawing Graph on web: jsPlumb.js

Background
jsPlumb is a open-source javascript library for drawing graph on web platform. FYI, please go in their official website http://jsplumbtoolkit.com/home/jquery.html. There are many demos and relevant documentations for you to start your development.

My opinions
To be honest, I have not read all of the documentations. However, in beginner point of view, their documentation is not programmer friendly and examples are quite hard to follow.

After working for few hours, I have written a test website to play around with this library. Here is the link: https://github.com/mondwan/jsplumb_test

Two things I would like to drop down after building up the above test page
1. No idea for why css position:relative is required for jsPlumb.draggable() function properly. Actually, I have reported it as a bug to jsplumb on github. However, they claim that this is not a bug.

2. jsPlumb.draggable() is not a pure wrapper which means jsplumb element cannot be updated correctly if you are using 3rd party dragging library. (I have struggle a while...)