I like this. It's eloquent and lovely; the only negative side to the whole poem is the last line. It's just a little cliche. Thanks for the review!

I love. The ending was my fav. part.

Okay, here's my explanation for the only negative thing I have to say about this: I don't understand poetry. I've never had Dr. Clark and I'm not sure what he's said about it, although I'm sure he's said quite a bit about it, but it's always managed to be beyond me if the poem doesn't have rhyme or meter. I don't understand the difference between this and prose with weird line-breaks. And so: I loved it. I thought it was great prose and incredibly well written, a little Della showcase for dialogue, description, and everything, all wrapped up in a nice, concise nutshell. I just like it better as prose.
(tell me about poetry later?)

I found this to be an enveloping experience that drew me into itself; I felt as though I were the narrator. I can find very little that I dislike about your poem, except perhaps for the last line. I'm of the persuasion that "staying whole" is a weak expression of a state of being. It's not really doing anything by staying whole, it's merely existing. I don't feel qualified to present an alternative, though for the life of me I wish I could think of one. I'm sure it will come to me later.
Also: "The light broke." How does light break, pray tell? Something can shield a light, thereby breaking its beam, but light itself does not break. Because you're talking about a window, the word break seems to fit here, but it doesn't. And at the end when the narrator sees the window, and prays that the glass stays whole, it is a misdirection. There was never any mention of the WINDOW breaking, just the light (as though it were possible). Why should he think about the window breaking, then? Should he not rather pray the light does not go out (I know, that would be a miserable ending, but it would at least be logical.)? It's a non-sequitur.
I think the aspect I most liked was the sudden starting and stopping in the beginning. I know the stained glass analogy is the main idea, but I found myself most enthralled by the pseudo-realistic dialogue. First it was so real, and then it became an abstract metaphor, still real in language, but poetic in theme. I enjoyed this piece immensely, and the minor flaws (or so they seem to me) detract very little from the overall impression. The poem was a success.