One example the company has developed is a crystal fibre that squeezes light into such a narrow core that the intensity of the light modifies the optical properties of the glass itself.
The front is literally a pane of polished glass and it exhibits the same properties -- oils and fingerprints are basically invisible when the screen's on, but they show up when off (and in the black zones above and below the screen).
Sheets of glass separated by a vacuum could bring windows' insulating properties up to par with insulated walls, yet allow them to be nearly as thin as single panes of glass.