bug#9350: 23.3; File menu should contain "split window horizontally C-x 3"

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> PS: One thing that annoys me in the current working of split-window: it
>> doesn't let you say which window (the top or the bottom) is the new one.
> The new one is that returned by `split-window', as before.

No, that's not the issue.  It's not about "which window (the
selected-window or the returned window) is the new one" it's "which
window (the top one or the bottom one)".

And the issue is not "tell me which it is" but "I want to control which
one it should be".

>> This was fine back when windows had very little state of their own, but
>> now it is important when it matters because of window-parameters,
>> window-dedicated-p, ...
>> So if we want to improve split-window, I think we should consider this
>> issue as well.
> Do you mean you need the identity of the new window when `split-window'
> is called indirectly by another function?  Maybe you could provide a use
> case?

No, here's the scenario: you have a dedicated window, and you want to
create a new window above that one: split-window won't work because it
will always create the new window below.


        Stefan