bug#16565: 24.3.50; x-popup-menu just returns nil

[Michael Heerdegen <michael_heerdegen@web.de>]

Eli Zaretskii <eliz@gnu.org> writes:

> If you start GDB in the src directory, or let it otherwise read the
> file src/.gdbinit, you can know for sure: the "xtype" command will
> tell you what kind of Lisp data is in 'selection':
>
>   (gdb) p selection
>   (gdb) xtype
>
> If "xtype" says it's a Lisp symbol, another command "xsymbol" will
> tell you what symbol is that, it will say "nil" if it is nil.

I don't have a command xtype, only ptype.  What do I miss?  Anyway, the
mouse tooltip over Qnil shows the same integer.

So I think xmenu_show returns nil in the bad case.

I continued debugging xmenu_show and found that after the call to
`create_and_show_popup_menu', `menu_item_selection' is only != 0 in the
good case.

I tried to step through `create_and_show_popup_menu' as well, but that
makes any input from X impossible at some point, I had to kill gdb from
the console.

Michael.