bug#52293: 29.0.50; [PATCH v3] Prevent further cases of duplicated separators in context menus

[Jim Porter <jporterbugs@gmail.com>]

On 12/9/2021 1:39 AM, Eli Zaretskii wrote:
>> From: Juri Linkov <juri@linkov.net>
>> Cc: jporterbugs@gmail.com,  52293@debbugs.gnu.org
>> Date: Thu, 09 Dec 2021 11:06:36 +0200
>>
>>> I'd prefer all of those to go to master.  I'm quite sure this is not
>>> the last time we hear that something in those quarters needs to be
>>> fixed (I think the feature wasn't mature enough to go to Emacs 28 in
>>> the first place, but that's water under the bridge now).  No
>>> catastrophe will happen if this will be fixed after 28.1, or even in
>>> 29.1.
>>
>> Do you think that [separator-global] should be renamed to [global-separator]
>> only in master?
> 
> Yes.  This way, we have quite some time before us to let people bump
> into any problems this could cause and report back to us.

That's ok by me. Note that this[1] is a very mildly incompatible change, 
so as long as people are aware of that, I think it should be ok to merge 
into 29, and hopefully into 28.2. The only incompatibility would be 
people wanting to add context menu items after certain specific 
separators like `global-separator' or `undo-separator'. I think that's 
fairly unlikely though, since:

a) `context-menu-mode' is new so there aren't many (any?) third-party 
packages that use it yet.

b) `context-menu-mode' doesn't guarantee that any particular items are 
actually present in the menu. Users can customize the context menu, so 
it could have anything at all in it. Relying on the presence of 
`global-separator' (however it's named) would be somewhat risky. 
`middle-separator' and `top-separator' (the latter is from the patch in 
this bug) are/will be at least *likely* to be present though, so are 
more likely to be used in third-party code.

If there are any other issues with the latest patch in this bug (or 
bug#52286), just let me know.

[1] bug#52286, that is.