I believe dragging the symbols can be done in GIMP. This month's challenge deals with maps that have those draggable icon qualities (if I understand VTT correctly), and I believe Torstan has shown maps with Draggable icons or tokens (on a different scale). If I recall, the suggetion in GIMP was to assign a layer to the icon you wanted to move, but keep that layer small (just large enough to hold the icon's image). Then, by selecting that layer and utilizing the move tool (four arrows in the tool box) you can drag it around. The problem, though, is that each layer adds to the file size, and I imagine you are talking about a large number of mobile units. It might be worth trying, with the unit layers being small it may not increase file size as much as I think. Look around, make a couple more posts (at 5 posts you'll be able to send and recieve private messages). I think Torstan's icons were in his dungeon tiles thread here http://www.cartographersguild.com/showthread.php?t=4721. In fact, VTT forum is one I rarely look at but you might be very interested in. Good luck, happy mapping, and don't forget to post something soon, I'd like to know what solutions you come up with, and see the results.