display-buffer change

["David Kågedal" <davidk@lysator.liu.se>]

I have seen a change in Emacs 22.1 from Emacs 21 that broke my use of
dedicated windows.

The problem is that (display-buffer buf) will change the contents of
the current window, if the other window in the frame has a dedicated
buffer.  In Emacs 21, a new window would be opened instead.

To see the difference, do the following:

Split an emacs frame in two windows showing buffers A and B:

   +-------------+
   |             |
   |      A      |
   |             |
   +-------------+
   |             |
   |      B      |
   |             |
   +-------------+

While in the lower window, run

    (set-window-dedicated-p (selected-window) t)

Now, in the upper window, run

    (display-buffer "C")

In Emacs 21, this will be the result:

   +-------------+
   |      A      |
   +-------------+
   |      C      |
   +-------------+
   |             |
   |      B      |
   |             |
   +-------------+

In Emacs 22, this will be the result:

   +-------------+
   |             |
   |      C      |
   |             |
   +-------------+
   |             |
   |      B      |
   |             |
   +-------------+

I use a dedicated small window at the bottom of my frame that always
contains the *compilation* buffer, and the new behaviour in Emacs 22
seriously lower the usability of a lots of command, such as viewing
diffs or showing source from gdb etc.

I didn't find anything in NEWS that indicated that this was somehow
intentional.

-- 
David Kågedal