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

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Stephen Berman <stephen.berman@gmx.net> writes:

> 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.

Could you please try to find out what this call to XtGrabPointer in
xlwmenu.c returns when you pop up a menu?

#ifdef emacs
  x_catch_errors (display);
#endif
  if (XtGrabPointer ((Widget)mw, False,
                     (PointerMotionMask
                      | PointerMotionHintMask
                      | ButtonReleaseMask
                      | ButtonPressMask),
                     GrabModeAsync, GrabModeAsync, None,
                     mw->menu.cursor_shape,
                     event->time) == Success) <-----------------
    {
      if (true

If you're going to be using a debugger, then please do the debugging
remotely from a different machine.  Otherwise, you will either lock up
your X server or waste a lot of time when the bug simply vanishes once
you try to debug it.

Either way, we have to get this fixed before Emacs 29 is released, so
please try to be fast here.  Thanks a lot.