Re: drag-and-drop failures

[Jan D.]

> It's good to see X drag-and-drop support added, but I think it needs
> explaining what is expected to work.  Also, presumably the TODO item
> on this can now be removed or be amended to say what still needs to be
> done.

I'll do that, thanks.  Does reading the Emacs manual about drag and drop
help to see what is supposed to work?

> I can drag text successfully from KDE applications, but not from
> Mozilla/Galeon, or OpenWindows.  I'm not surprised OpenWindows won't
> work, but NEWS talks about drag and drop `under X' generally.

I know of six different drag and drop protocols under X, but Motif and
XDND are the most common.  I didn't want to confuse people in NEWS by
being too technical.  I planned to add OpenWindows, but I skipped that.
I don't use OpenWindows any more and it is on its way out, so the effort
does not seem worth it.

> ASCII characters dragged from Galeon (built for GNOME) or Mozilla get
> converted to U+FFFD in Emacs.

I can not reproduce this.  Did you start emacs with -q --no-site-file?
Also try setting the environment variable LANG and/or LC_ALL to C
before starting emacs and see if the problem is still there.
What version of Mozilla/Galeon/GNOME are you using.  I tried Mozilla
1.6, Galeon 1.3.7 on GNOME 2.4.

> Dragging text from CDE dtpad (running on Tru64) to Emacs (on Debian)
> crashes Emacs:

Is it only dtpad or any CDE application that craches Emacs?

> Program received signal SIGSEGV, Segmentation fault.
> 0x70345b04 in _X11TransWrite () from /usr/X11R6/lib/libX11.so.6
> (gdb) bt
> #0  0x70345b04 in _X11TransWrite () from /usr/X11R6/lib/libX11.so.6
> #1  0x70325ca4 in _XFlush () from /usr/X11R6/lib/libX11.so.6
> #2  0x70327304 in _XReply () from /usr/X11R6/lib/libX11.so.6
> #3  0x70322558 in XSync () from /usr/X11R6/lib/libX11.so.6
> #4  0x000959a8 in x_catch_errors_unwind (old_val=5615712)
>     at /dl/sr/homes/px/fx/esrc/src/xterm.c:7714
> #5  0x00120dc0 in unbind_to (count=400, value=541020088)
>     at /dl/sr/homes/px/fx/esrc/src/eval.c:3082
> #6  0x00095b70 in x_connection_closed (dpy=0x661198, 
> error_message=0x3ec400 "")
>     at /dl/sr/homes/px/fx/esrc/src/xterm.c:7905
> #7  0x00095db8 in x_error_quitter (display=0x661198, error=0xefffe6a0)
>     at /dl/sr/homes/px/fx/esrc/src/xterm.c:7943
> #8  0x00095dfc in x_error_handler (display=0x661198, error=0xefffe6a0)
>     at /dl/sr/homes/px/fx/esrc/src/xterm.c:7958
> #9  0x70329240 in _XError () from /usr/X11R6/lib/libX11.so.6
> #10 0x70327660 in _XReply () from /usr/X11R6/lib/libX11.so.6
> #11 0x7030eb70 in XGetAtomName () from /usr/X11R6/lib/libX11.so.6
> #12 0x000aa4ac in x_atom_to_symbol (dpy=0x661198, atom=2157853552)
>     at /dl/sr/homes/px/fx/esrc/src/xselect.c:290
> #13 0x000ac788 in selection_data_to_lisp_data (display=0x661198,
>     data=0x6095d0 "", size=18, type=4, format=536870911)
>     at /dl/sr/homes/px/fx/esrc/src/xselect.c:1655
> #14 0x000ac5e0 in x_get_window_property_as_lisp_data (display=0x661198,
>     window=37748766, property=305, target_type=541247376, 
> selection_atom=1277)
>     at /dl/sr/homes/px/fx/esrc/src/xselect.c:1574

Hmm, the atom passed to x_atom_to_symbol looks like garbage.  And the
type passed to selection_data_to_lisp_data is 4, which means Atom.
Atom is 4 bytes, but size is 18, not a multiple of 4.  Strange.
Can you do this again, and when it crasches, go up to stack frame 14
(x_get_window_property_as_lisp_data) and print out all local variables
as well as doing pr in gdb on the Lisp_Object variables and parameters?
This assumes you start gdb from the emacs/src directory.
I'll need the output from xlsatoms also.

It might be a 64 bit thing, but I am not quite sure how.

Thanks,

        Jan D.