Drag Column top position out of alignment with table.

[sitesense]

I actually thought this was a feature at first but now think it's a bug.

I've fixed this by changing the following line:
elementOffsetTop = self.element.position().top;

To this:
elementOffsetTop = self.element.offset().top;

"position()" calculates the element position relative to the offset parent,
where "offset()" calculates the element position relative to the document.

[jebaird]

@sitesense I can see where that could be a bug. In the tests that I when the table is contained in a div that has its position set to relative and the scroll to overflow it causes drag display to "jump" down. Whats is the markup / css that's causing this?