bug#54289: 29.0.50; Emacs ignores xmodmap Super_L assignment

[Stephen Berman <stephen.berman@gmx.net>]

On Tue, 08 Mar 2022 18:10:45 +0800 Po Lu <luangruo@yahoo.com> wrote:

> Stephen Berman <stephen.berman@gmx.net> writes:
>
>> AFAIK Xfce4 uses Gtk3, and e.g. xfce4-terminal and thunar (file manager)
>> recognize my Super_L mapping to `/'.  LibreOffice does too.  The only
>> other program I use that ignores Super_L is Firefox, but it has since
>> long before this Emacs problem started (with your commit 15910e5d
>> according to git bisect); I've search the web about this Firefox issue
>> but haven't found anything.
>
> Interesting, but please see below.
>
>> Of these, Emacs fails to recognize only the Super_L mapping, since the
>> above-mentioned commit.  (As an experiment I added `remove Super_L =
>> Mod4' before the Super_L = slash mapping, logged out and back in, but
>> the result was that none of the .Xmodmap mappings were recognized, not
>> just in Emacs but also e.g. in xfce4-terminal.  So I removed that line
>> to restore the status quo ante.)
>
> Can you show the output of running just `xmodmap' without any arguments?

xmodmap:  up to 4 keys per modifier, (keycodes in parentheses):

shift       Shift_L (0x32),  Shift_R (0x3e)
lock
control     Control_L (0x25),  Control_L (0x42),  Control_R (0x69)
mod1        Alt_L (0x40),  Meta_L (0xcd)
mod2        Num_Lock (0x4d)
mod3
mod4        slash (0x85),  Super_R (0x86),  slash (0xce),  Hyper_L (0xcf)
mod5        ISO_Level3_Shift (0x5c),  Mode_switch (0xcb)

> I suspect that some modifier is mapped to Super_L, alongside slash.

Is the above output consistent with the five mappings in my .Xmodmap
file?

> That is incorrect, so Emacs and Firefox are within their rights to
> ignore such a mapping.

If so, how do I get the mapping of Super_L to slash back (at least in
Emacs)?

Steve Berman