[X3D-Public] What is the behavior of Touch/Drag sensors when occluded?

[Dave A]

Let's say you have an object that has a TouchSensor on it. It happens to 
be behind a (let's say) semi-transparent object. Maybe that material has 
a texture that looks like chain-link fence or maybe it's a window.

Should I be able to touch it?

I don't see anything in the spec that really addresses this.

What I would hope for in a knee-jerk way is, it would let me pick 
'through' transparent textures. But I realize this is a dicey 
proposition to make a blanket rule.

So my next thought is that it would let me pick through anything that 
doesn't also have a sensor like that on it. But again, easy to find 
examples of why that's not good.

So ultimately, what I expect, is some sort of boolean or node or 
something that says 'ignore for picking' or something to that effect.

Anyone know if Contact has such an option?

Dave A