While I am wishing…
I think it would be really nice if VASSAL could draw lines between pieces. These could be used to show unit formations (e.g. a platoon HQ units could have a line from it to all its squads (ala the way Combat Mission did it in their old version). Or one could use it to show who is firing at who. If either one of the two pieces moves connected by a line moves the line would be redrawn to reflect the new pieces location. It would be nice to be able to have layer for these lines so as to change color or make them dashed etc. It would be nice to be able to change these lines within the game by right clicking on each piece and having menu commands to add/delete/show/hide, etc the line between them. One could use these lines to mark routes as well by connecting apiece to way point pieces.
And extra “bonus” feature that might be neat would be the ability for the length of the line (in say hexes) to be computed as a property for the line so that it could be used to trigger events.