Wiktionary
n. (context idiomatic English) valuable feature (of software etc) overlooked by the user
Wikipedia
The ruby slippers are the magic pair of shoes worn by Dorothy Gale as played by Judy Garland in the classic 1939 MGM musical movie The Wizard of Oz. Because of their iconic stature, the ruby slippers are now considered among the most treasured and valuable items of film memorabilia. As is customary for important props, a number of pairs were made for the film, though the exact number is unknown. Five pairs are known to have survived; one pair was stolen in August 2005 and has never been recovered.
In L. Frank Baum's original novel, The Wonderful Wizard of Oz (1900), on which the film is based, Dorothy wears Silver Shoes. However, the color of the shoes was changed to red in order to take full advantage of the new Technicolor film process being used in big-budget Hollywood films of that era. Film screenwriter Noel Langley is credited with the idea.
"Ruby Slippers" is the eighteenth episode of the fifth season of the American fantasy drama series Once Upon a Time, which aired on April 17, 2016.
Usage examples of "ruby slippers".
Barnes was only the most recent to own a pair of sequined shoes known as the Ruby Slippers, worn by one of the characters in the film, but he considered them to be the gem of his collection.
Barnes died alone and without heirs, so it seems certain to be a while before the Ruby Slippers find a new owner.
Well, the Necroscope didn't have any ruby slippers, but he did have the Mobius Continuum.
On her feet were shining ruby slippers, a crown adorned her freshly coiffed, newly dyed scarlet hair, and on her back, the cause of her uneasy posture, were a pair of huge, filmy wings, tinted garnet red, iridescent as soap bubbles but more durable than fast-food condiment packets.
I don't have the ruby slippers, but I got me some shining black leather boots, don't I?
To Martin, they were as potent as Hitler's shirts, or Judy Garland's ruby slippers, or Jackie Kennedy's pink pillbox hats.
I look down to see why she is clattering and I see: ruby slippers.
Hysteria grabbed her throat as images of gingham and plaits and sparkling ruby slippers bobbed up and down in her mind.