Re: Revise etc/DEBUG documentation

[Noam Postavsky <npostavs@users.sourceforge.net>]

On Sat, Sep 3, 2016 at 9:14 AM, Alain Schneble <a.s@realize.ch> wrote:
>>> +When using X, type C-z at the window where Emacs is running under GDB,
>>> +and it will stop Emacs just as it would stop any ordinary program.
>>
>> The "window where Emacs is running under GDB" part is IMO confusing: I
>> couldn't figure out what window does this refer to.  There might not
>> be such a window at all, AFAIU.
>
> To be honest, I don't understand this either.  But this was there
> before.  I just took it over and rephrased it slightly.  For example C-z
> in Gnome just minimizes the window (Emacs frame) AFAIK, but doesn't stop
> Emacs.  Do you know what C-z usually does in X window with a GUI
> application?  Does it send a signal to it?

There's no special meaning of C-z for X windows. Emacs binds it to
`suspend-frame'. The "window" in question here is the window of the
terminal emulator where gdb was started from. In this case hitting C-z
while Emacs is running gives back to the debugger (by sending SIGTSTP
apparently)

(gdb) run
Starting program: /home/npostavs/src/emacs/emacs-master/src/emacs -Q
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0x7fffe959a700 (LWP 23870)]
[New Thread 0x7fffe8981700 (LWP 23871)]
[New Thread 0x7fffe3fff700 (LWP 23872)]
^Z
Thread 1 "emacs" received signal SIGTSTP, Stopped (user).
0x00007ffff0b1918c in pselect () from /usr/lib/libc.so.6
(gdb)