I just tested and yes, it blinks the cursor, I was able to highlight some of the areas, but some not. Also, noticed that these areas are made of tons of points, so guess we need a more efficient is inside point method and a form to do a better arrangement of closed areas and points to use. This goes more into the use of a kd-tree -- on my closed polygon custom object, that can have internal loops and big areas that form the object, maybe like these entities, where the user can pass the cursor and each of these areas that form the closed polygon are highlighted (via a solid hatch, and different color depending on the type of area)... anyway if I can will give it a try later today -- but at least we know what works or not.