While looking at a bug report, I found that the current GUI for the Action
Constraint actually didn't make sense, mixing up settings so that it wasn't
clear which settings corresponded to which others. This commit cleans up the
layout into a clearer two-column design to have a "from" -> "to" layout, making
all the
relationships between things clear.
For more details see http://aligorith.blogspot.com/2012/01/action-constraint-
gui-revised.html