Workspace chooser showing transparent view

[Robert Moskowitz]

Don't know how to explain it well, but after coming out of suspend mode, 
the workspace chooser on the panel is showing the windows behind the 
active one kind transparent.

I do not recall setting anything like this, though I did install a 
testing version of thunar for my bug on mounting my phone back on friday.

Anyway, I recall a setting for showing hidden windows in a transparent 
mode, but I can't find it.

Any help greatly appreciated.