Problem with this map resource

Need some help from anyone that has installed this map resource
http://www.garagegames.com/index.php?sec=mg&mod=resource&page=view&qid=11084

I have this mod installed and working. My problem is the Arrow does not reflect where my player currently is on the map. I am assuming the problem lies in the last 2 lines of this gui control definition.

new GuiMapView(MapView) {
Profile = "GuiDefaultProfile";
HorizSizing = "width";
VertSizing = "height";
Position = "1 22";
Extent = "400 400";
MinExtent = "8 2";
Visible = "1";
screenShotMode = "0";
bitmap = "~/data/maps/Stronghold.png";
wrap = "0";
arrowBitmap = "./mapArrow.png";
topLeftPos = "-840 580";
bottomRightPos = "880 -1170";
};

My Question is how do I find the topLeftPos and bottomRightPos of my mission to define for the map. I am using the default Stronghold mission.