bug#28194: text-scale-adjust should show current accumulated scale factor

[Juri Linkov <juri@linkov.net>]

reopen 28194
quit

>> I think it is more likely an emacs bug, that something I set in my
>> http://jidanni.org/comp/configuration/.emacs
>> wipes out the functionality.
>
> Could you please provide a minimal recipe for how to reproduce this,
> starting from "emacs -Q"?

I can reproduce this bug.  Running either "emacs -Q" or without "-Q"
after loading all customizations from init file it works correctly:

1. C-x C-=
2. there is "+1" in the mode-line
3. and evaluation results:

text-scale-mode
=> t

text-scale-mode-lighter
=> "+1"

(assq 'text-scale-mode minor-mode-alist)
=> (text-scale-mode (" " text-scale-mode-lighter))

But after several hours of active Emacs session
this feature breaks and doesn't work anymore even in new buffers:

4. C-x b new-buffer RET
5. C-x C-=
6. there is NO "+1" in the mode-line
7. and evaluation results:

text-scale-mode
=> t

text-scale-mode-lighter
=> "+1"

(assq 'text-scale-mode minor-mode-alist)
=> nil

Since this feature is so unreliable, maybe we should duplicate
the scale factor information in two places: in the mode-line
and in the message in the echo area.

Stefan, after you pushed your patch that supports changing font size
using mouse wheel, now would it make sense to do also what web browsers do
- on pressing C-+ they momentarily display information about new percentage
in a small window.  In Emacs this information could be added to the message
in the echo area, e.g. replace

  (message "Use +,-,0 for further adjustment")

with

  (message "%s Use +,-,0 for further adjustment" text-scale-mode-lighter)