Re: bug of display-table & make-glyph-code

[Stefan Monnier]

>> I must have lost too much context: I do not understand the
>> above description.  Can someone spell it out in baby-steps for my poor
>> excuse for a brain?

> The OP explained it as follows:

>> 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      |
>> +-------------+
>> 

> What he apparently wants is window B always display the same buffer, stay
> below all other windows, and not change its size.

I guess I see the following problems:
0 - it's not clear to me why Emacs chooses to split B rather than A.
    It seems unrelated to the split-height-threshold fix, so we need to look
    into this before being able to determine how best to fix it.
1 - since we're in buffer/window A, it would probably be preferable to place
    buffer C closer rather than further, so in this case after splitting B
    display-buffer should prefer using the top window for C and the bottom
    one for B.
2 - "dedicated" is mostly meant to cause deletion of the buffer to also
    cause deletion of the window.  It says nothing about the window having
    a fixed size or being non-splittable.
3 - we have window-size-fixed for that.
4 - we don't have window-(un)splittable for that (there's a frame parameter
    to prevent splitting windows in that frame, tho).


-- Stefan