When I use the mouse to move a SystemWindow to a new position, the mouse
down produces a square frame that moves with the hand position, and the
mouse up makes the frame go away with the SystemWindow being relocated
to the new position.

In most cases, the new position of the SystemWindow is the position to
which it was moved with the mouse. However, if the new position is at the
top of the world PasteUpMorph, possibly conflicting with the world main
docking bar or the Sugar navigator bar, then the new SystemWindow position
is modified to avoid the top region.

Where is the code that figures out the new position in the case of a
SystemWindow being dragged to the top of the world PasteUpMorph? I am
trying to debug a window positioning problem in one of my images, and
I cannot figure out where the magic happens.

Thanks,
Dave