[Amber H.]

A company came up with an invention that sounds lke what you're talking about. The glass would change colors or go opaque when you touched either a button to control it or the glass itself.
I don't know if they even exist anymore. the company name was "Reliant Laser" of some city in the San Francisco Bay area (I'll have to look it up, it's been over ten years now). But they had an origional patent on something like this.

There was also some talk a few years back in the housing industry about special windows that would become opaque with the use of lcd technology. Look up window manufacturers. that might give you a good start.

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I think it was "Reliant Laser of Foster City". All I remember is that my self appointed godfather/family friend whom I worked for at the time dragged me along to a meeting to pose as his personal secretary to make him look important (he was too cheap to hire a real one). (The information isn't proprietary anymore so I can say all this.) -Anyway They dealt mostly with laser technology and as a result had to develop special safety goggles that could instantly change to adjust to thier new machine that could produce several different kinds of laser beams for medical procedures instead of the doctor having to get a whole new machine to finish whatever procedure. The basic idea was that the doctor could switch beams and safety glass values mid-procedure, without getting up to get a whole new laser machine from accross the room or changing his goggles. It was pretty cool.