On Wed, Mar 14, 2012 at 1:41 PM, David Maus <dmaus@ictsoc.de> wrote:

Hi,

At Tue, 13 Mar 2012 14:49:41 +0800,

Du Yanning wrote:
> org-mode 7.8.03
> emacs 23.3, 23.4, 24.0.94
>
> steps to recreate:
>
> emacs -q
>
> copy the following code and paste it into the *scratch* buffer:
> (add-to-list 'auto-mode-alist '("\\.txt\\'" . org-mode))
> (add-hook 'org-mode-hook '(lambda () (text-scale-set 4)))
>
> M-x eval-buffer
>
> then C-x C-f to open a .txt file, and then C-x C-f to open another .txt file.
> Every time a .txt is opened, the font size become larger and larger.
> However, the indicator in the mode line remains +4.

I can confirm this behaviour but I don't think this is an error. The
description of `text-scale-set' reads:

C-h f text-scale-set RET

,----
| text-scale-set is an interactive autoloaded Lisp function in
| `face-remap.el'.
|
| (text-scale-set LEVEL)
|
| Set the scale factor of the default face in the current buffer to LEVEL.
| If LEVEL is non-zero, `text-scale-mode' is enabled, otherwise it is disabled.
|
| LEVEL is a number of steps, with 0 representing the default size.
| Each step scales the height of the default face by the variable
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| `text-scale-mode-step' (a negative number decreases the height by
| the same amount).
`----

The first time `org-mode-hook' is run the height of default font is
scaled by 4 levels, i.e. the height of default font is set to a new
value. The second time `org-mode-hook' is run the height is scaled
again, this time based on the new value. And so on.

If you want to set the face height you might use:

(set-face-attribute 'default nil :height 100)

Here `100' means 100% of the font size in pt (afaik).

Best,
-- David
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