bug#38007: scroll-lock binding on Windows

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

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>> Did you succeed in figuring out where does the "Scroll_Lock" text come
>> from?  It isn't in lispy_function_keys[] array.  On MS-Windows,
>> "scroll" does come from that array.  That's what I meant by that
>> remark.
>
> Oh, I see.  No, I don't know where it's coming from.

It's from get_keysym_name in xterm.c.

> I thought that we (under X) got the key symbols for (some) keys from
> X, and didn't maintain the database ourselves?  So we can basically
> get any symbol that the X people dream up.

Yes, and that database is huge.  "Some" of those symbols have to be
treated specially; see the big block of code under KeyPress and
XI_KeyPress in handle_one_xevent that tries to handle the most common
ones might run across.  It starts with:

 	  /* Random non-modifier sorts of keysyms.  */
 	  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
                        || keysym == XK_Delete


That list is hardly exhaustive, and a few new keysyms were added
recently that I haven't gotten around to looking at yet.