Scrolling doesn't work

If you create an scrolling container and put a sortable in it, then make the window fullscreen on a Mac by clicking the green dot in the window bar, you cannot scroll down by dragging an item near the bottom edge. You can scroll up but not down.

This line returns very different values when the window is in fullscreen or not:

( this.overflowOffset.top + this.scrollParent[ 0 ].offsetHeight ) - event.pageY < o.scrollSensitivity

Offsets seem to be the culprit.