Now scroll preventDefault works more like default browser scroll.
When the scroll leaches top, bottom, left and right end, don't
prevent default scrolling. For sure, when the content size is
smaller than the container size, also don't prevent default scrolling.
Changed the height and widths calculations of the content div to
include any padding and/or margins.
outerHeight(true) is changed to outerHeight(false).
outerWidth is changed as same.
Fixed by noraesae.
Ensure the panel is at the top after an update where the scroll bars
are removed. Other wise it is possible to get stuck midway down a panel
with no way of scrolling.
