bug#15336: Bad computation of window height

[Sebastien Vauban]

Hello,

Just wanted to inform you that the bug #15336 is still reproducible in
Emacs 24.4 and Emacs 25.0.50.1.

One side note though: I have 2 screens, and they are set up one above
the other (physically and logically).

  |----------------------|
  | screen #2 (external) |  <-- 1680 x 1050
  |----------------------|
  | screen #1 (laptop)   |  <-- 1920 x 1080 (Full HD)
  |----------------------|

That may impact what I see on Emacs 25.0.50.1.

With the following code:

--8<---------------cut here---------------start------------->8---
  (when (display-graphic-p)

    ;; put Emacs exactly where you want it, every time it starts up
    (setq initial-frame-alist '((top . 0) (left . 0)))

    ;; auto-detect the screen dimensions and compute the height of Emacs
    (add-to-list 'default-frame-alist
                 (cons 'height
                       (/ (- (x-display-pixel-height) 106)
                          (frame-char-height))))

    ;; maximize Emacs by default
    (modify-all-frames-parameters '((fullscreen . maximized))))
--8<---------------cut here---------------end--------------->8---

I'm expecting to have Emacs maximized at startup, on the main screen,
that is occupying the full space of screen #1: 1920 x 1080.

What I get, instead, is an Emacs frame of (1680 + 1920) x 1080... whose
top-right corner is located at the top-right corner of screen #1 (hence,
I don't even see its full height, without minimizing and re-maximizing
it first).

Best regards.