This is a different way of covering scene changes than that used, for instance, in La Boheme at the Met, designed by Franco Zeffirelli. He just dropped the curtain. This, I must say, interrupted the drive of the story and led to extended stare-at-the-curtain breaks for the audience that were enlivened only by a few mysterious bulges and quiverings of the heavy velvet. Well and, each time, another curtain call... a series of ovations that began to get more and more amusing; just how much applause can an opera singer stand to listen to anyway?
La Boheme is absolutely gorgeous! with dramatic set changes well worth a little wait... but it was designed in 1981 and, with its curtain drops and highly romantic scenery, it feels a little old-fashioned. (No artist ever starved in a lovelier Parisian garret.)
This modern trend to never to close a stage curtain, however, relies on sleight-of-hand.
By one of those funny coincidences, as I was driving away from this meeting and thinking about the magic of manipulating the audience's attention, a talk show on my car radio was interviewing the author of the book Fooling Houdini. This talks about magic and, in part, about the glitches in human perception which make magic work. I'd read the book! Unfortunately, it didn't have a chapter titled "These are Things a Set Designer Needs to Know." When reading the amusing travails of the author, I suppose I should have taken notes. I enjoyed the book; it turns out, we're all very easy to fool.
Optical illusion - believed public domain, found HERE.
Speaking of the quirks of human perception... Seen this video of a classic example of the (embarrassing) gaps in human perception? Have fun with "The Selective Attention Test": HERE.