Hi, Morwen - I don't believe the phrase "in the closet" surfaced until the late 20th century, as a phrase meaning to conceal one's sexual orientation.

I believe there were "monster in the closet" or "bogeyman" stories in which the creature in the closet was supposedly black.

But I don't think that either of these had anything to do with what was said about Irving Berlin. I think the implication was that his music was "black," as in written in an African-American style.

I thing the "pickaninny in the closet" bit was just to add impact to the insult, but I think maybe it's best not to read too much into the comment. "Back in the day," people made racial comments like that all the time and thought nothing of it. I remember being embarrassed by the way my grandmother talked about other races, and she didn't have a hateful bone in her body - that's just the way people talked back then.

-Joe-