Oh, I have mentioned it. Since it doesn't appear to be in the FAQs, here it is all in one place:
I was at a convention in Chicago, when I heard DC was planning a book about the history of Batman. I was not under contract to Marvel at the time, and I had a three month "window" upcoming into which I could fit such a project, so, since I had wanted to do Batman since, like, for-everrr, I contacted the editor and told him I was available.
A short time later, one of the Powers That Were at DC got in touch with me, saying they would be thrilled to have me work on the project, but unfortunately they would not be able to match my Marvel page rate. No problem, said I. This was Batman! I would just about do it for free. So I agreed to do the series, and Terry Austin signed on (figuratively) to ink.
Then I waited for the plot for the first issue. And waited. And waited. The whole first month of my three month window went by, with nothing forthcoming. Finally, into the second month, the plot arrived. I was a little disappointed to see it was basically a "cut-and-paste" story, requiring me to do little beyond redrawing previous scenes, but it was BATMAN! And I really wanted to do Batman. I looked at my schedule and decided I could fit the four issues into two months, provided there were no further slips.
I got the first issue penciled, and it was lettered and even shown to Terry, who was in the office around this time. And I waited for the second plot. And waited. And waited.
The third month of my three month window slipped into the Past. The window closed. I called the editor and said I would not be able to finish the project. He said he could get me the first half of the second plot in "a week or two" if I could just be patient. I reminded him that I had said from the beginning I had three months in which I could do this. The three months were gone. I could no longer do it.
Then, the same Higher Up who had called to tell me that they could not match my Marvel rate called to offer me double my Marvel rate if I would finish the job. I bristled at this -- where was all this extra money suddenly appearing from?? -- and still declined.
When the project was finally announced, DC added insult to injury by reporting to the fan press that I had "quit" the project unexpectedly, that Jim Aparo was being called in to finish, and to ink "Byrne's very loose pencils" on the first issue. Terry, who, as noted, had seen the first issue, sent around a couple of letters to various 'zines informing them that the pencils were every bit as tight - ie, very -- as what he was inking on X-MEN.
It was a long time after that before I felt like doing anything for DC again.