Background dim?

[Geralt]

I remember (think) seeing a video a while back which showed that when you have a window selected, it darkens everything else on the screen. I'm wondering how you do this, or if it's even possible... it may have just been my imagination. (Not that I have a very good one)

If you don't know what I mean - basically;

• The window on top, which you have selected stays the same brightness, but everything else behind it which isn't selected dims out.

 

[Orbital Shark]

There's only the 'Aero Peek' function, highlight an active app icon on the taskbar then hover the mouse over the thumbnail preview. It sounds like a 3rd party app that may have been running, something from StarDock maybe