Remember these windows? They're sweet, respectable and downright demure during the day ... but just look at how wildly they glam it up at night.
There's a metaphor here somewhere.
Maybe Browning had it figured out when she wrote,
"Yes," I answered you last night;
"No," this morning, sir, I say:
Colours seen by candlelight
Will not look the same by day.
Or maybe it's just fun to find the drama in things. (Even stained glass windows.)