We just recently acquired the PRO version, but seems there is an issue with the scroll on Firefox that is not present on the examples you provide in your documents page. For some reason the vertical scroll is not correct on Firefox, it is very slow, Chrome is correct and IE is not displayed at all.
I just found this was introduced on the PRO version provided, and not in the version running on your examples, here is a fiddle with both version provided, try running on Firefox and you will see the problem.
http://jsfiddle.net/gvazq82/12dpct1b/41/
Please let me know how to fix this issue.