How do I focus on objects, so my view because darker, except for the selected object?

Hey guys,

I was someone using Omnigraffle and noticed that everything he selected got some kind of focus… His whole canvas became darker, except for the object he selected. Some kind of lightbox effect on websites, where you’ll see something you can focus on.

Hopefully you guys understand m. Really want to figure this out… :)

This only happens on grouped objects. If you have a group you can double-click on one of the elements and you’ll get exactly that effect. Everything remains grouped and you’re editing the one thing that isn’t darkened.