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

[martin rudalics]

>    (set-frame-width nil width nil t)
>    (message "%s" (cons width (frame-text-width))))

Sorry.  Without the ‘sit-for’ this is confusing.  So this

(let ((width (frame-pixel-width)))
  (setq frame-resize-pixelwise t)
  (set-frame-width nil (+ width 20) nil t)
  (sit-for 2)
  (set-frame-width nil width nil t)
  (sit-for 2)
  (message "%s" (cons width (frame-pixel-width))))

is bad while this

(let ((width (frame-text-width)))
  (setq frame-resize-pixelwise t)
  (set-frame-width nil (+ width 20) nil t)
  (sit-for 2)
  (set-frame-width nil width nil t)
  (sit-for 2)
  (message "%s" (cons width (frame-text-width))))

should do what you want.

martin