The phrase "a propos of nothing" is correct and usable in written English.
It is typically used to introduce a statement or comment that is unrelated to the current topic of discussion.
Example: "She suddenly mentioned her favorite book, a propos of nothing, leaving everyone in the room puzzled."
Alternatives: "out of the blue" or "without any context".
A propos of nothing in particular, Roger says: "BBDO have just hired their first negro.
2 50pm: A propos of nothing, let's have none of this today.
You were sitting in the back, aged about four, with the window open when, a propos of nothing, you suddenly announced that Wol had fallen out.
But he is beginning to compete with Ronald Reagan for citations in Republican speeches and debates, often a propos of nothing.
He denied attending one overnight visit, calling it a "slumber party," but also added, apparently a propos of nothing, that the estate was where he met the author J.K. Rowling.
If "Advise and Consent" is not technically an election film, the odor of anti-Obama rhetoric hangs thick and pungent over the hornet's nest surrounding its pivotal cabinet nominee, Robert A. Leffingwell, a liberal of flawed if well-meaning service who, in the wake of the death of the secretary of state, has been tapped by the president (a back-room smoker, a propos of nothing) to fill the post.
For months afterwards, when one might, for example, finish buying a round of drinks by asking 'What about you, Syd?' he would declaim, in a firm but affectless way: 'I like it in the head.' Sometimes when a conversation briefly faltered he would nod wisely and, a propos of absolutely nothing, say it again.
3 40pm A propos of absolutely nothing, Michael Lowman says this: "I'm really looking forward to this game... but what I really want to mention is that Hemel Hempstead council wouldn't empty my wheelie bin this week because it wasn't on my boundary.
He also included, à propos of nothing in particular, "the rough sketch of a mad dog, presented me, for this work, by (the late) Sir Anthony Carlisle".Hawker was aware of safety.
"I freaked out and locked myself in the bathroom," he explained, a propos of an earlier radio interview.
One last word a propos of diversity outside of Hollywood in the mainstream: the most depressing sign is that so-called overseas box-office hotspots like Mexico, Russia and Brazil are producing virtually nothing that looks remotely like crossing over, few new populist directors of note like Alfonso Cuáron, Timur Bekmambetov or Fernando Meirelles, and pitiful market shares for local films.
