What are the "objects it detects" and the "selected objects list"? Are you saying that solid/obstacle objects are not in the list of objects to check for LOS?
It only checks for points so a large solid will do no good, since it only has 1 point...(Im guessing)
If it's not detecting solids you may have to add "obstacles" manually in your events.
That would give me an easy arc and distance check, but it doesn't account for obstacles. I'd need to manually check if LOS to an object is blocked by another object.
Well distance(x1,y1,x2,y2) will give you that, but to get a line of sight you can take a rectangular object that can do collision detection, scaled to the range, and always pointing the same angle as the sprite, then have a collision event if the detector is overlapping an obstacle.