RE: select and META key

["Herbert Euler" <herberteuler@hotmail.com>]

>However, there is surely a bug.  Since you press the Meta key
>only before releasing mouse-1, the event is slightly different from
>pressing the Meta key before pressing mouse-1: in the former
>case the first event is `down-mouse-1', and in the latter the
>first event is `M-down-mouse-1'.  Although the outcome is the
>event `M-drag-mouse-1' in both cases, `mouse-drag-secondary'
>seems not to get executed and other secondary selection
>relating commands, such as `mouse-yank-secondary' fails to be
>executed.

I solved the bug, more or less.  To reproduce the bug, follow these
steps:

1. Run Emacs in a window system and switch to the *scratch* buffer.

2. Press mouse-1.

3. Drag the mouse to somewhere else, and press the Meta key.  With
   keeping mouse-1 pressed in the whole progress.

4. Now release mouse-1 with holding the Meta key.  You will see the
   secondary selection is made.

5. Move point to the end of the *scratch* buffer, and press M-mouse-2.

Although there are secondary selected text (showed by an overlay in
the *scratch* buffer), you cannot yank it at all.  This is because
when `mouse-set-secondary' gets executed when a `M-drag-mouse-1' event
is generated at the end of the above steps, the `SECONDARY' property
of symbol `x-selections' is not set correctly (actually it is nil).

The below patch solves the problem.

*** mouse.el.~1.241.8.44.~	2007-03-19 09:11:41.000000000 +0800
--- mouse.el	2007-03-28 11:26:41.000000000 +0800
***************
*** 1522,1528 ****
      (with-current-buffer (window-buffer (posn-window posn))
        (if (numberp (posn-point posn))
  	  (setq beg (posn-point posn)))
!       (move-overlay mouse-secondary-overlay beg (posn-point end)))))

  (defun mouse-drag-secondary (start-event)
    "Set the secondary selection to the text that the mouse is dragged over.
--- 1522,1532 ----
      (with-current-buffer (window-buffer (posn-window posn))
        (if (numberp (posn-point posn))
  	  (setq beg (posn-point posn)))
!       (move-overlay mouse-secondary-overlay beg (posn-point end))
!       (x-set-selection
!        'SECONDARY
!        (buffer-substring (overlay-start mouse-secondary-overlay)
! 			 (overlay-end mouse-secondary-overlay))))))

  (defun mouse-drag-secondary (start-event)
    "Set the secondary selection to the text that the mouse is dragged over.

However, there are several questions I want to ask:

[1] Is the patch appropriate?  Although I have tested it, it may cause
    other potential problems.

[2] I do not read all code in mouse.el.  Are there other possible
    problems like this one?

Thanks.

Regards,
Guanpeng Xu

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