Hi, all.

a part taken from a magazine:

In the streets of Kreuzberg and Neukolln, one of Berlin's toughest immigrant areas, there don't seem to be many angry young men wandering around. In these largely Turkish neighborhoods, the young are more focused on finding opportunities to improve their lives. And, after decades of neglecting the guest workers who were supposedly going home one day, Germany is beginning to help them. It was a long time coming.

I construe the boldfaced sentence to mean: It was/took a long time [for the help] to come or The help took a long time to come. Assuming I am right, the use of an -ing form admittedly bothers me. Is it simply an idiomatic way of saying it?

Best regards,
Yes, this is a reasonably common stock phrase, Komountain.

Koizumi has at last secured passage of his postal privatization bill in the Diet, and it was a long time coming. (= it took a long time to accomplish/come into being)
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You are right, that sentence is a fixed expression, used, I believe, largely in American English. I came across it a long time ago in one of the songs by Sam Cooke titled, if I am not mistaken, "A change is gonna come". I am not too sure whether it was he who coined the expression "It's been a long time coming". But it seems to me that it is largely identified with what is termed Black English. "It's been a long time coming" means it is taking a long time to come or to be achieved.

Thanks, guys.

I am happy to wrap up another day learning something new.