In my module, I have set all the map windows to fire an “alt W” combo each time a piece ends it’s movement on a map.
In a trigger on a card, I have set it to fire a report every time “alt W” is detected, i.e. when this card gets dragged around from one map to another. The property match I have specified is $CurrentMap$ != $OldMap$. However, when I move the piece around within the same window, the trigger still fires. So even though CurrentMap and OldMap are the same, the trigger fires. I have placed a text label on the card to check what the properties $CurrentMap$ and $OldMap$ are and it reports that they are the same.
I am using Vassal 3.2 beta 3 and have entered this as bug 4836.