Undocking a draggable not under the mouse

Undocking a draggable not under the mouse

I would *really* appreciate some help on what to do about this:  http://jsfiddle.net/Trober/URudt/23/

Problem: the draggable is not under the mouse when undocking it.

1. Drag the "Drag-n-Dock Me" block to touch the north/top boundary.  

2. Drop it in that position; it should dock itself against the north/top boundary.

3. Drag it away from the north/top boundary.  The draggable is not under the mouse, and remains flush against the left boundary.

Thanks,
Ben