overriding completion's choice of which window to use

[Jonathan Epstein]

Hi,

Suppose I have an Emacs frame with the following window layout

AAAAAAAAACC
AAAAAAAAACC
AAAAAAAAACC
AAAAAAAAACC
AAAAAAAAACC
BBBBBBBBBBCC
BBBBBBBBBBCC
BBBBBBBBBBCC
BBBBBBBBBBCC
BBBBBBBBBBCC

and the current buffer is A.  When minibuffer completion takes place, Emacs
invariably chooses buffer C, but I really want it to always choose buffer B.

To provide more detail, I never want the minibuffer completion to occur in
buffer C.  E.g., in the diagram above if the current buffer is B, I want
completion to occur in buffer A.  Also, if there are are just two windows, A
and C:
    AAAC
    AAAC
    AAAC
    AAAC

I want it to split A for the minibuffer completion, much as it would do if C
were not present.

I always know the title of window C in advance, and would like to know how
to protect it from the fate of becoming a minibuffer completion window.  Or,
for that matter, from becoming a compiler output window, etc.

TIA,

Jonathan