bug#31745: Frame's bug when window-system

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This bug occurs in both emacs 26.1 in the official archlinux repo and emacs-git 27.0.50 in aur when i am using MATE 1.20.0 with its default window manager.

My configuration about frame size in .emacs is as follows:

(add-to-list 'default-frame-alist '(top . 0))
(add-to-list 'default-frame-alist '(left . 0))
(add-to-list 'default-frame-alist '(width . 120))
(add-to-list 'default-frame-alist '(height . 47))
(add-to-list 'default-frame-alist '(font . "Sarasa Mono CL 12"))

If i launch emacs with a file in terminal, such as `emacs .emacs` or run `emacs --geometry 120x47`, all works will.

But in other cases, such as launch emacs in terminal using command `emacs`, emacs will display a smaller frame in its default size, but text area will treat itself as if it is actually in an 120x47-size frame. For example, it will not show mode line, because the mode line is "displayed" on line 46, but the frame is actually 80x36 and if one line in scratch has more than 80 charactors, it will not display `right-arrow` or `right-curly-arrow`.

I also try to add `(x-parse-geometry "120x47+0+0")` in file `.emacs`, but it doesn't work.