RE: frame-set-background-mode changes frame background for special-display frames

[Drew Adams]

    I should add that the problem does not always occur. Sometimes
    (but not always), after first starting Emacs, the
    special-display frames are correctly displayed with their
    intended backgrounds. I have not been able to determine the
    exact conditions for the bug to manifest itself. However, it
    seems that once the problem develops it continues; that is,
    once the wrong background appears, all such buffers/frames will
    have incorrect backgrounds thereafter (even if deleted and then
    recreated).

Sorry for the incremental description, but here's some more info:

If I have a special-display buffer, say *grep*, in a special-display frame
that has the correct special-display background (e.g. after starting Emacs
and running `grep'), and I then delete the frame (with or without also
killing the buffer), and then I use `grep' again, then this second time the
*grep* frame is created the background is incorrect (it is the background
color of the default-frame-alist).