How do I turn off the feature where a window grays out when it's thinking?

So in the last couple of releases of Ubuntu (forget when it started), a window will gray out if it is not responsive/thinking too hard. Maybe "gray out" isn't the best term, it just sort of gets darker. I'm not sure what the exact criterion is to set this off.

For one program in particular (Mathematica 8.0) this gets annoying because the program grays out whenever I rotate a 3D plot for more than a couple of seconds.

Is there a way to turn this feature off, and even better, only for specific programs?

Pictures of before I start rotating, and while I'm rotating are below, in case my description is not clear. This only rarely happens with other programs, so I have no idea how to reproduce it if you don't have Mathematica.

Solution 1:

Oh sorry for the thing I took otherway. Now I understood your problem. Graying out unresponsive window is an inbuilt feature with option, which you can turn off. It comes for compiz, which worked for me with the following tweak:

Go to System -> Preferences -> CompizConfig Settings Manager -> Effects -> Fading Windows and then just to option for Dim Unresponsive Window and you can set the option as per your requirement.

More changes about compiz can be found here. Not sure about gnome.