slowMode and draggables/droppables

slowMode and draggables/droppables


What is the purpose of slowMode (the property of a draggable) and why
does it depend entirely on whether the mouse cursor is inside the
element being dragged?
The context of this question: I've been working with UI on a project
that uses drag and drop style interaction to lay items out on a
screen. Most of the items are dragged around via a handle that sits on
top (vertically, not in front of) the element being dragged. This has
been fine, but once I started trying to drop items into various
containers, I started having trouble. It seems that if the draggable's
slowMode property is set to false, the drag/drop manager's fire method
(which in turn fires the drop event on droppables) is never called
(ui.draggable.js, lines 140 and 153). This seems like some strange
behavior (maybe just overzealous optimization?). The only other place
slowMode is checked is for the iframeFix option on a draggable (again,
I'm not sure I feel clear on its purpose here).
As a side note, I'm also curious about options.dropBehaviour, which is
checked in the same place slowMode is in order to fire/not fire the
drop event, but appears never to be set or used in any purposeful
manner.
Thanks for any insight you can provide.
-Rob