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).

More info, possibly related:

If I do M-x grep from a buffer in a frame that has a small (e.g. tiny) font
size, then buffer *grep* is opened in another frame (because I use non-nil
pop-up-frames) with the same tiny font size. That is, the new frame does not
use the default font size; instead, it uses the font size of the previous
frame. This does not happen in previous releases of Emacs.