drag and drop

I would like to learn how xerte successfully enables drag and drop on smart phones. Can you furnish me a link to the code in github where you have a drag and drop exercise (for example: categories) so I can see how you did this. I am unable to get drag and drop to work on a smartphone if I write something in javascript.
thanks,
Jon

The code for the categories exercise can be found in modules/xerte/parent_templates/Nottingham/models_html5/categories.html

This file is dynamiically loaded by the modules/xerte/parent_templates/Nottingham/common_html5/js/xenith.js

Thanks, Tom. Are you able to point me to the area of the code or css that is specific to mobile devices. Just those lines that are unique for the touch screens?