Descriptive Problem Summary: On map large enough to exceed the view port, using the Move/Select tool on an atom that is partially out of view will result in the atom being moved several tiles away from its previous location.

Numbered Steps to Reproduce Problem:
1) Download the following test project: http://files.byondhome.com/Higoten/Tests/ Move-Select%20Tool%20Shift.zip
2) Navigate to map.dmm and locate the black turfs with the red turf in the upper-left corner.
3) Position the red turf in the upper-left corner of the view port, so that the red turf is not fully visible on both the x and y axis.
4) Using the move/select tool, click on the red turf.
5) Observe that the map viewport has moved significantly and that the red turf is now several diagonal tiles away from its previous location.

Expected Results: For the atom to become selected and remain in its current location.

Actual Results: The atom is repositioned in an area several tiles away.

When does the problem NOT occur? The issue does not occur if the atom is already selected using the move/select tool; the map shifts as expected. The issue also does not occur if the atom is not partially located outside of the viewport.