Found a bug (edit: okay nevermind it isn't a bug):
http://www.filedropper.com/hittinglinebug
The sprites falling should all turn green, but only one does (because it overlaps the corner??).
I want to query first hitting line for all the falling objects to know when another object is beneath them. Seems as if this doesn't work as expected.
edit: on further analysis, it appears that it only triggers when the line is entering the object. It doesn't trigger if the line begins within the object.
Is there a way to check if a point resides within an object? , then I could use that along with the line check.
edit2: okay I found a way to solve it. I used two more short lines pointing down at the corners.