bug#21480: 25.0.50; Frame width gets set to 16 pixels wider than the provided width in the args

[martin rudalics <rudalics@gmx.at>]

 > (defvar bkp--frame-height-px nil)
 > (defvar bkp--frame-width-px nil)
 >
 > (defun modi/toggle-menu-bar ()
 >    "Toggle the menu bar.
 > Also restore the original frame size when disabling the menu bar."
 >    (interactive)
 >    (let ((frame-resize-pixelwise t))
 >      ;; If the menu bar is hidden currently, take a backup of the frame
 > height.
 >      (when (null menu-bar-mode)
 >        (setq bkp--frame-height-px (frame-pixel-height))
 >        (setq bkp--frame-width-px  (frame-pixel-width))

Here you use "pixel sizes" again.  You have to use the "text sizes".

 >        ;; `frame-pixel-width' is returning a value higher by 16 pixels
 > compared
 >        ;; to that set using `set-frame-size'. So the below adjustment has to
 > be made.
 >        ;; (setq bkp--frame-width-px  (- (frame-pixel-width) 16))
 >        )
 >      (menu-bar-mode 'toggle)
 >      ;; Restore frame size if menu bar is hidden after toggle
 >      (when (null menu-bar-mode)
 >        (set-frame-size nil bkp--frame-width-px bkp--frame-height-px
 > :pixelwise))))
 >
 > (global-set-key (kbd "<f2>") #'modi/toggle-menu-bar)
 >
 > I noticed one more thing.. In my emacs setup, I need the adjustment of 16
 > pixels (as shown in the code above).
 > But in an emacs -Q session, I need an adj of 32 pixels. That might probably
 > help narrow down the problem.
 >
 > Does it have to do with the fonts I use? Because emacs -Q starts with
 > Dejavu Sans Mono font. Whereas my configured emacs uses PragmataPro font.

This means that the scroll bar + fringes widths differ in these setups.

BTW, setting ‘frame-inhibit-implied-resize’ to '(menu-bar-lines) should
allow to toggle the menu bar without any resize of the outer frame.

martin