Meet the new unfocused state of Ambiance and Radiance in Ubuntu 12.04
Usability-wise unfocused state is a new quality implemented into Ubuntu's light themes, Ambiance and Radiance, attribute that brings a modern behavior suitable for a fancy desktop.
Basically, the new unfocused state is: a window in fullscreen mode and focused mode is displayed with orange checkboxes, highlighted text, selected entries, etc, but, if another unmaximized window is opened, the fullscreen window enters in the new unfocused state, meaning, all the orange items become a light gray, so the unfocused state is "adopted" by the window on almost all of its regions (the "old" behavior takes the focus only from the close/minimize/maximize buttons from the titlebar).
The light themes' new unfocused appearance is definitely a solid plus in usability, users can easily interact with focused windows in an almost distraction-free environment, the fullscreen window is exposed as a soft colored "background".
At the moment, the above behavior is usable only with fullscreen windows versus focused yet unmaximized windows.