When "Nudge as Pixels" was selected in the map editor, Alt+click and Alt+drag still set step_x/y coordinates instead of pixel_x/y. Additionally, nudge left changes step_x.
Numbered Steps to Reproduce Problem:
1-2
Expected Results:
When Nudge as Pixels is enabled, Alt+Click, Alt+Drag, & Nudging should not change step_x/y
Actual Results:
Alt+Click & Alt+Drag w/ Nudge as Pixels Enabled (Ignore cursor - there was a problem in recording the .gif)

The alternative was to possibly place the object as normal on the map, then use the nudge hotkeys. This works in all cases except Nudge Left.
Nudge Left:

Nudge Right:

Nudge Right, Nudge Up, Nudge Down work as intended.
Does the problem occur:
Every time? Or how often? Every time
In other games? N/A
In other user accounts? N/A
On other computers? Yes
When does the problem NOT occur?
Did the problem NOT occur in any earlier versions? If so, what was the last version that worked?
Will test further and follow-up on the latest working version.
Workarounds:
Unknown
http://www.byond.com/forum/?post=2195204
http://www.byond.com/forum/?post=2379454