IMDB lists "Broadway Nights" as the 1st film of Sylvia Sidney.
at lunch at Kent's Stag Bar many years ago I mentiond to SS that I'd read she made her movie debut in this 1927 silent movie whose star was my friend Lois Wilson. Miss Sidney told me that she'd actually first appeard the year before as an extra in Lothar Mendes' "Prince of Tempters" with Lois Moran (best rememberd today as the starlet behind F. Scott Fitzgerald making a screen test).
altho I haven't read everything ever written abt Sylvia Sidney I don't recall this information being publishd. so it occurrd to me to set it in print.
next day addition (esp for Stephen):
she came to the university for a performance. in addition to lunch I treatd her to a post-perf party at my house. she was a witty lady but sharp of tongue which didn't endear her to everyone. (& yes.... I once had hair.)