Resizing EchoArea of Emacsclient

Question

I am facing a strange problem. After I change the KDE window rules for emacs according to http://www.emacswiki.org/emacs/KdeMaximized, that is, I created a special window setting:

the size of echoarea (the area shared with minibuffer) is doubled by default whenever the font size is larger than 115 (1/10 pt):

,

while normally it should be like this:

Moreover, this only occurs when emacsclient is maximized and without menubar (it is fine when fullscreened or not maximized or with menubar). Maybe it is just a problem with KDE? But I couldn't find other way to fully maximize KDE without creating special window settings.

Surely a workaround is to set font size to be at most 115, but that looks too small on my 13.3 ultrabook and I usually set it to 125.

So I am just wondering if there is a way to resize the EchoArea (or change the font size of EchoArea.) by emacs settings? I tried adjusting the font size of the minibuffer, but it does not work since only the minibuffer font is changed while the Echoarea is not affected.

I am using emacs 24.3.

Thanks!

Answer 1

Explanation

Emacs cannot fully use arbitrary screen sizes because it (for the most part) displays a grid of characters.

As a simple example, consider characters that are each 10 by 10 pixels, and screen real estate of 1024 by 768. You'll have four pixels of width and eight pixels of height that cannot be used by Emacs.

The article you linked to is about forcing Emacs into a particular screen size. From the page:

Once you try to maximize the window, emacs resizes itself to a slightly smaller portion of the screen. This is because emacs rejects the geometry given to it by KWin, because it’s not an integral multiple of the width/height of one character.

When you tell KDE to force a particular size, the Emacs frame ("window" in non-Emacs terminology) will be the size you want, but the windows inside it ("splits" in non-Emacs terminology) may not fit properly. This usually leads to "wasted space" at the bottom of the screen like you are seeing.

As you noticed, changing your font size can give different results. If your character width is 8 pixels, for instance, you won't have any wasted horizontal space since 1024 divides by 8 evenly (128 times).

Similarly, going fullscreen and enabling the menubar both alter the amount of vertical space that Emacs has available for its windows.

Workaround

One workaround might be to adjust the size of your KDE taskbar. I believe it can be adjusted with single pixel granularity. If you adjust it smaller by a few pixels one at a time you should find a small adjustment that will make Emacs use its space more efficiently.

Answer 2

A you suggested, you might try to alter the font size of the minibuffer:

(add-hook 'minibuffer-setup-hook 'my-minibuffer-setup)
(defun my-minibuffer-setup ()
       (set (make-local-variable 'face-remapping-alist)
          '((default :height 0.9))))

(via Altering the font size for the Emacs minibuffer separately from default emacs?)

This will make the font size just a bit smaller. Try playing with the height and see if it can resolve the issue...