bug#33320: 27.0.50; `describe-key' fails to display help for C-mouse-3

[Glenn Morris]

Richard Stallman wrote:

>   > I don't think we can do that with all toolkits, because once Emacs
>   > pops up the menu, the toolkit has control.
>
> Are any of the supported display methods not worth supporting any more?
> In principle, we could drop any that users don't care about any more.

This has been discussed before, see eg https://debbugs.gnu.org/26180 .
The Motif and "no toolkit" toolkits are very little used
(see eg https://debbugs.gnu.org/stats/emacs.html).
The Lucid/Athena toolkit is a bit more popular. I use and like it
myself, but would be willing to see it go if it made life substantially
easier for the people maintaining these areas of Emacs.
I also think GTK+ v2 could go, frankly, though that could be a bit contentious.
That would leave only GTK+ v3 (ie, support only the current stable GTK+).

But that's all irrelevant since the people working on these areas feel
differently, see bug#26180 again.