GNU bug report logs - #76321
31.0.50; Moving nested child frames out of their child parents

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From: martin rudalics <rudalics <at> gmx.at>
To: Gerd Möllmann <gerd.moellmann <at> gmail.com>, 76321 <at> debbugs.gnu.org
Subject: bug#76321: 31.0.50; Moving nested child frames out of their child parents
Date: Sun, 16 Feb 2025 10:00:25 +0100

[Message part 1 (text/plain, inline)]

>> An observation: When I modify the frame creation like this
>>
>> (defun tty-3 ()
>>    (interactive)
>>    (setq tty-3
>> 	(make-frame
>> 	 `((parent-frame . ,tty-2)
>> 	   (left . (- 30)) (top . 5)
>>                     ^^^^^^
>> 	   (width . 10) (height . 5)
>>
>> and then do M-l and C-M-l, tty-3 is displayed at a different location
>> than after the modify-frame-parameter. This is an indication that there
>> is an inconsistency somewhere.
>>
>> Elisp info says about frame parameter 'left':
>>
>>       ‘(- POS)’
>>            This specifies the position of the right frame edge relative
>>            to the right edge of the display or parent frame.  The integer
>>            POS may be positive or negative; a negative value specifies a
>>            position outside the screen or parent frame or on a monitor
>>            other than the primary one (for multi-monitor displays).
>>
>> Parent frame tty-2 of tty-3 has
>>
>> 	 `((parent-frame . ,root-frame)
>> 	   (left . 40) (top . 5)
>> 	   (width . 30) (height . 20)
>>
>> tty-2's right edges is at 40 + 30 = 70, in root coordinates.

Hopefully.

>> So, the right edge of tty-3 should land at 70, which makes its left edge
>> should be 70 - 10 = 60.

The right edge of tty-3 should land at 70 - 30 = 40 in root coordinates
and its left edge at 40 - 10 = 30 in root coordinates which means, given
that tty-2's left is at 40 in root coordinates, tty-3 should be
invisible.

>> That is absolutely not what I'm seeing, neither with the initial (- 30)
>> for left nor after modify-frame-parameters. So I guess my reading of
>> Elisp info is wrong?
>>
>> Martin, could you please help me with this? What is the intended effect
>> of the (- 30), do you know?

The old code in tty_child_pos_param is wrong.  I'm using


tty_child_pos_param (struct frame *f, Lisp_Object key,
		     Lisp_Object params, int pos)
{
  struct frame *p = XFRAME (f->parent_frame);
  Lisp_Object val = Fassq (key, params);

  if (CONSP (val))
    {
      val = XCDR (val);

      if (TYPE_RANGED_FIXNUMP (int, val))
	{
	  pos = XFIXNUM (val);

	  if (pos < 0) ; <------------ see here !!!!!
	    /* Handle negative value. */
	    pos = (EQ (key, Qtop)
		   ? p->pixel_height - f->pixel_height + pos
		   : p->pixel_width - f->pixel_width + pos);
	}
      else if (CONSP (val) && EQ (XCAR (val), Qplus)
	       && CONSP (XCDR (val))
	       && TYPE_RANGED_FIXNUMP (int, XCAR (XCDR (val))))
	pos = XFIXNUM (XCAR (XCDR (val)));
      else if (CONSP (val) && EQ (XCAR (val), Qminus)
	       && CONSP (XCDR (val))
	       && RANGED_FIXNUMP (-INT_MAX, XCAR (XCDR (val)), INT_MAX))
	pos = (EQ (key, Qtop)
	       ? p->pixel_height - f->pixel_height - XFIXNUM (XCAR (XCDR (val)))
	       : p->pixel_width - f->pixel_width - XFIXNUM (XCAR (XCDR (val))));
    }

  return pos;
}


and am still not entirely convinced that it's right.  I attach my
current changes.

martin

[child-frame-menubar-drag-resize.diff (text/x-patch, attachment)]

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