bug#6956: 24.0.50; pasting mouse selection in other session pastes only first word

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: Drew Adams <drew.adams@oracle.com>, 6956@debbugs.gnu.org
> Date: Tue, 31 Aug 2010 14:13:30 -0400
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Select some text (several words) with the mouse using double-click
> >> mouse-1 on one word then mouse-3 on a later word in the text.
> >
> > Does this constitute a "mouse drag"?  Can someone please tell what
> > happens on X with the recipe in this bug report?
> 
> Yes, this follows the rule that if the region is highlighted, the
> primary selection is set.  On X, if you double-mouse-1 on a word and
> extend the region with mouse-3, you can use mouse-2 to paste the entire
> selection into another application.

The issue here is that mouse-drag-copy-region is advertised to copy to
the kill-ring regions which are highlighted by dragging the mouse.
But mouse-drag-copy-region only affects mouse-drag-region (via
mouse-drag-track), which is bound to mouse-1.  Mouse-3, OTOH, is bound
to mouse-save-then-kill, which is not affected at all by
mouse-drag-copy-region.

So when Drew double-clicks mouse-1, the highlighted first word is
indeed copied into the kill ring (and winds up in the clipboard), but
extending the region with mouse-3 doesn't copy the extended region.

What I think happens on X under mouse-drag-copy-region is that the
first word is copied into the clipboard, while the extended region is
copied to the PRIMARY selection by the code in command_loop_1 which
catches active regions.  Can you please verify this?

If my guess is correct, then I think this is a bug: we should copy the
whole region to the kill-ring when mouse-drag-copy-region is non-nil.
That is, if extending the region with mouse-3 as described in this
report indeed constitutes a "mouse drag".