on the curved lines, might think about having it be a three point line placement. first click beginning the curve, the second being the mid point of the curve and the last click being the end of the curve.
might also consider having an option (hold left alt and click) to close your line segments in case you were creating on the map. This could be used to designate a route for patrol and then looping it. This would come in handy having multiple fire teams patrol areas, designating their routes in color in the event that their designated patrols overlap or intersect each other. It's just the small detail of closing it that would get under some of our skins. (not being nit-picky)
I do like your mod and would like to know if you have a potential release date for the update? I am particularly waiting for the delete option.
