bug#14795: height parameter inconsistent in new vs existing frames when tool-bar is enabled

[Juanma Barranquero]

Package: emacs


This happens since at least 22.1, and I think has been discussed
before on emacs-devel, but I've been unable to find the reference.

  emacs -Q

 (let ((params '((height . 25))))
  (make-frame params)  ;; f1
  (modify-frame-parameters (make-frame) params))  ;; f2

  f1 = 28 lines
  f2 = 25 lines

Adding (tool-bar-lines . 0) to params, both frames are 25 lines.

Obviously, when creating the frame Emacs is allowing three additional
lines as space for the toolbar. tool-bar-mode defaults to 3 in a newly
created frame, at least once it has been displayed:

(let ((f (make-frame)))
  (cons (frame-parameter f 'tool-bar-lines)
        (progn
          (sit-for 0)
          (frame-parameter f 'tool-bar-lines))))

=> (1 . 3)

Does that happen in all platforms? If so, shouldn't we make the
meaning of the height frame parameter consistent in all its uses?