Re: display-buffer change

[David Kågedal]

martin rudalics <rudalics@gmx.at> writes:

>> 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.
>
> [...]
>
>> 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.
>>
>
> Please ignore if this has been already resolved.  You should be able to
> handle this by customizing `split-height-threshold' to a reasonable
> value (say 10).  Confer the doc-string of `display-buffer':
>
>   If a full-width window on a splittable frame is available to display
>   the buffer, it may be split, subject to the value of the variable
>   `split-height-threshold'.

I'm sorry for the late response, this came just as I was going on a
longish vacation, and I seem to have forgotten about it.  I just tried
setting split-heigh-threshold to 10, and the behaviour changed, but
not to the Emacs 21 behaviour.  I'll copy my original description, and
append the new behaviour:

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      |
   |             |
   +-------------+

In Emacs 22 with split-heigh-threshold=10, this will be the result:

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

I'm not sure how well this will work for me in practice, but I think
at least it's an improvement.

-- 
David Kågedal