bug#58771: 29.0.50; context submenu can not click when run emacs lucid build.

[Stephen Berman]

On Tue, 25 Oct 2022 18:30:36 +0800 Po Lu via "Bug reports for GNU Emacs, the 
Swiss army knife of text editors" <bug-gnu-emacs@gnu.org> wrote:

> Feng Shu <tumashu@163.com> writes:
>
>> just right click in emacs buffer.
>
> I managed to reproduce a hang trying to click on the submenu item, but
> then killed Emacs in an attempt to reproduce the problem again, and it
> stopped happening.  Since that, I haven't been able to reproduce the
> hang.
>
> So it would be nice if you could try to find a way to reproduce this bug
> from "emacs -Q", because I'm really lost.

I can reliably reproduce the bug, but for me it's a sympton of broader
buggy behavior with menus in the Lucid build, which I've observed since
I started regularly building with the Lucid toolkit some months ago
(after not doing so for many years previously, so I don't know how old
this behavior is).

So while the items of a context menu (but not those of a submenu) can be
scrolled with the mouse, context menus are completely unresponsive to
keyboard events.  In contrast, with menus from the menu bar (whether
open via mouse click for with the F10 key binding), I can both navigate
and select (also in submenus) with the keyboard but other than opening
and closing, the menu bar menus are completely unresponsive to the
mouse.

Here's my current build info:

In GNU Emacs 29.0.50 (build 15, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.17.6, Xaw scroll bars) of 2022-10-25 built on strobelfs2
Repository revision: 92ec31a48c7fa2a700eb3a5c618fe015843e6875
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Linux From Scratch r11.0-165

Configured using:
 'configure -C --with-x-toolkit=lucid --with-xinput2 'CFLAGS=-Og -g3'
 PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM
XINPUT2 XPM LUCID ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix