However if you were using the attribute to group your obstacles you can add those objects to a family, and use the family instead.
I'm using the "solid" attribute to block movement, not for any kind of grouping.
Keep in mind los does not add objects it detects to the selected objects list.
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?
On number two:
The behavior works off of points, basically its the same as distance(x1,y1,x2,y2), only it can detect if something is in between those two points.
I checked out the code and confirmed this. Thinking about it more, LOS logic that accounts for the size of the object is non-trivial. Nevertheless, it would still be really nice to have.
There is a work around that does not use the behavior. That being a detector sprite that you have scaled to the to the range of sight.
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.