I'm going to bump this because there's been no replies and I still think it's a good idea, though my explanation probably didn't do it justice.
Basically I was trying to make a custom platform movement and realised I absolutely hate using other sprites as detectors, there's too much fiddling around with hotspots and size changes etc, they just get annoying. So I tried to use the "object overlaps point" condition to replace these detectors, only to find its extremely limiting and unsuitable for this purpose.
For a detector on the right, I set the single point to the midpoint of the sprite on the Y axis, and the furthest right point on the X axis, but because it's just a single point at your midpoint if you collide with something on your feet or your head it doesn't stop you. I thought for a second about looping it through every Y, then realised that was dumb since collision detection must handle a bunch of points at once anyway.
You should be able to (at the very least) specify 2 X values, and 2 Y values, and it tests collisions within the region between them (a box), thus giving removing the need for invisible detectors.
It might be nicer in fact to have >3 (x,y) coordinates, and test a polygon between them, allowing the creation of weirder shapes that might be more useful.
The reason I was suggesting sets is that you could potentially describe different shapes other than some n sided polygon (like a circle). Though, the syntax would probably be ultra confusing, and might be hard to implement.