1039212 - intl.accept_languages not configurable in the GUI after usage of defaultPref

Status: UNCONFIRMED

(Firefox :: Settings UI, defect)

Description

[laurent.bierlaire]

User Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E; InfoPath.3)

Steps to reproduce:

Configure intl.accept_languages with a cfg file.
Ex. defaultPref("intl.accept_languages", "en-gb,de,fr");


Actual results:

When checking the about:config we can see that the default value is properly applied and websites use the preconfigured language.
But in the GUI the preferred language apprears empty, and it's not possible to add any additional language.


Expected results:

The languages configured with defaultPref should be visible and user modifiable in the GUI.
When configured as a pref instead of a defaultPref then they are visible and user modifiable, but of course any change is lost lost when Firefox is closed.
This bug also exists in 17.x & 24.x ESR.

Comment 1

[NtH]

Bug still present in latest beta release. More details:


Steps to reproduce

- Download latest beta release (62.0b19 as of now)
- Create `autoconfig.js` and `mozilla.cfg`

$ cat browser/defaults/preferences/autoconfig.js 
// empty
pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0);

$ cat mozilla.cfg
// empty
defaultPref("intl.accept_languages", "en");

- Create new profile
- Run Firefox using the new profile
- Open `about:config`, check that the default `intl.accept_languages` pref is set to the value in `mozilla.cfg`
- Open `Preferences` -> `Language` -> `Choose...`


Actual results

The `Choose...` dialogue opens, but the list is empty. The browser console logs

TypeError: preference.value is null    languages.js:143:9

Adding new languages to the list is not possible. The following is logged in the browser console

TypeError: preference.value is null    languages.js:194:9
addLanguage   chrome://browser/content/preferences/languages.js:194:9
oncommand     chrome://browser/content/preferences/languages.xul:1:1

Comment 2

[NtH]

Tested in Arch Linux amd64.

Comment 3

[NtH]

Workaround found here:
https://github.com/pyllyukko/user.js/pull/253

  defaultPref("intl.accept_languages", "data:text/plain,intl.accept_languages=en");