Is "Use Look-At Limit" for func_buttons new? It lets you prevent accidental presses of clusters of buttons.

As the title says, I can't find any reference to this on the internet. I discovered it at random and when I tried it out it really improved clusters of buttons. I'd rather press nothing than a button across my screen, which is usually what ends up happening with this value at the default 0.8 and a few buttons near each other.

Here's a picture: http://i.imgur.com/Vz7Ow7I.png