I bought a stained glass light fixture that has one broken panel. I'm sure one of you talented readers can tell me the best fix.

That looks like what they call lead came....I never learned that technique.......If it was the copper foil method, I could help....You might want to take it to a stained glass place and let them take it look at it...It can be fixed though...:)

Thanks for the info.

I'm cheap. I was hoping for a easy fix.

sorry to have the only easy/cheap fix is sto turn the cracked side to the wall.....

After I glue a piece of plastic under the crack????

And I'm not beyond doing that!

There is a tube of glue that works on glass, ceramic, jewelry...I can't remember the name...but E-2000 seems familiar...anyone????

I do stained glass and unfortunately, the only way to repair it is to remove the broken part and replace. There is a way of using copper foil on the top and bottom of the break and creating a faux lead line but I'm thinking that considering the piece, it would also be too pricey a fix. You could ask your local hardware store or go online for glass glue. It is made specifically for cracks in glass, though usually somewhat less extensive than this and hardens in the sun (ultraviolet). Personally I follow the advice of an earlier poster and turn that side toward the wall.

Could it be repaired using the same way they fix a chip in a windshield?

Yes, E2000 will glue anything, I repaired eye glasses that lasted another year when the optician told us there was no glue that would hold up to eye glasses.
And the repair would be very expensive, turn it to the wall, I would probably not even bother with fixing it at all.

Avoid putting the glue on the lead. If you ever decide to have the glass replaced, you will not be able to remove it without damage to the lead came. New came will standout like a sore thumb.