Re: Better handling of window margins

[martin rudalics]

>> You say that linum-mode will specify a "display width of the same N
>> columns in pixels".  How would it react to an increase of the width of
>> the default face?
>
> How is it covered today?

Via ‘post-command-hook’ I suppose.

>> IIUC this is not covered by any special hook so it has to be done
>> via ‘post-command-hook’.  No great deal but it shows that
>> ‘post-command-hook’ is indispensable for such modes.
>
> Even if this conclusion is correct, is it really relevant to the
> concrete issue being discussed?

Hopefully.  If we want to get rid of ‘post-command-hook’ dependencies.
If we don't care, it's obviously not relevant.

> If the only problems we could think
> about, after my suggested solution is implemented, are the ones that
> don't have any good solution now, it means the main problem -- how to
> allow several features request display margins without stomping on
> each other's toes -- is most probably solved.  Then the other problems
> should be considered and solutions for them sought.
>
> IOW, what I suggested wasn't supposed to solve any problem except one:
> how can several features display simultaneously on the same display
> margin.  It wasn't supposed magically solve other related or unrelated
> problems.

How does the ability to specify a margin size in pixels help to display
several features simultaneously?  I'm all for specifying margin sizes in
pixels.  But then I have no idea why we should keep the "character cell
units" specification.  And obviously a transit to pixel specification
has its price.

>> So you mean there's no need for any new infrastructure here - the
>> ‘split-window’ window parameter can take care of this.
>
> I simply don't believe there could be a generic solution that doesn't
> involve active participation of the modes that are affected by this.

If modes can specify their needs for each window they act on, the
overhead will be encapsulated in calculating a window's minimum width.
If we can't manage that, then modes will also have to intervene every
time we set a window's fringes or scroll-bar width or adjust its right
trailing edge.  I'm afraid that mode authors won't want to do that.

>>   >> When two modes simultaneously use the margins, which buffer display
>>   >> function would be chosen?
>>   >
>>   > The same problem exists with the proposed solution, doesn't it?
>>
>> Is there one?
>
> Of course: imagine that the effects of 2 or more elements of the list
> contradict each other.  Which one to choose?

I thought Joost's idea was to capture this issue by having
‘window-splittable-p’ count static margins only.  So I don't see any
contradiction.

martin