If scrolling parent is not body the scroll lock functionality does not work.

[mikekoser]

I propose allowing the scroll parent element to be supplied as an option. This allows other elements to used in place of body as the scrolling parent. In my case it was the html element that had the overflow scrolling. In addition to that in order for the unlock scroll logic to behave on popup close we would need the ability to supply the object containing all of the CSS properties to apply to the parent scroll container to effectively put it back the way it was prior to the popup opening. I have made these changes locally, but will fork & apply the changes in git.