Horizontal Sortables failing on variable height elements

Horizontal Sortables failing on variable height elements


I have composed a horizontal container of linked lists, each
containing sortable elements. The horizontally linked lists themselves
are also sortable. (See demo).
(Demo) http://www.inovasdesign.com/TestApp2.html
In this example, click "add element" maybe 5-6 times to get a
sufficient length that cannot be sorted with other elements. If you
remove elements (drag them to other columns), that list will become
sortable again.
In my demo, you can add columns and elements.
My problem arises when one list becomes too long. It seem sortables
sorts from the middle of every element, not the top. So, in my demo,
once the middle of an element is below the bottom of another element,
that first element will no longer sort.
(To test this problem, copy my code and remove axis: 'x'. Then, get a
list that's too long to sort, and drag it vertically up so that the
center of that list touches the other lists. Its sortable again!)
This is fixed if a define a static height for all lists, but that's a
horribly ineffective fix. (Just define what, 1000px so no one makes a
list that large, and never put anything below the lists, since there
will be a massive buffer).
Is there a way to a) Limit the height while sorting, b) use a helper
style element that replaces my list with a placeholder while sorting,
c) increase the height for all horizontal lists while sorting, or best
of all, realign the sort axis with the top of the element, not the
middle?
Again, you can see the code/demo here: http://www.inovasdesign.com/TestApp2.html
Thanks!