Invisible characters in the admin in Opera 12

[SergeyBiryukov]

See the screenshot.

If the loaded font subset doesn't contain some characters (bold Cyrillic characters in this case), Opera fails to apply the standard serif font and displays nothing instead. This was extensively tested for Twenty Twelve in #21751 and #21775.

The solution is to load the correct font subset: tags/3.7.1/src/wp-content/themes/twentytwelve/functions.php#L98​.

We should probably also add the ability for translators to disable Open Sans, like we did for Twenty Twelve.

[SergeyBiryukov]

Related: #26072

[iammattthomas]

In 26254:

Load the correct subset of Open Sans for cyrillic, greek, and vietnamese in addition to latin and latin-ext; following the example of Twenty Twelve. See #26063, props SergeyBiryukov.

[iammattthomas]

Thanks Sergey; I'd been meaning to steal this logic from Twenty Twelve. Even if we decide to bundle, we'll still want to include this if we give people the option of linking, plus it fixes the issue immediately and bundling still has a number of open questions.

[iammattthomas]

Left this ticket open for the option to disable Open Sans for translations.

[matt]

Let's get a way to disable Open Sans for translations in this week or table it for 3.8.1.

[dimadin]

Attached patch implements disabling from translations as it's done in Twenty Twelve, Twenty Thirteen and Twenty Fourteen. Also changes to new braces style for subsets and uses add_query_arg().

[SergeyBiryukov]

In 26376:

Allow Open Sans to be disabled per language. props dimadin. fixes #26063.

[dd32]

We can't use add_query_arg() in script-loader, infact, we have to avoid as many functions as possible.

This is because we include script-loader.php within wp-admin/load-styles.php for style concatenation in build versions.

Fatal error: Call to undefined function add_query_arg() in build/wp-includes/script-loader.php on line 588

Fix incoming.

[dd32]

In 26381:

Revert the change to use add_query_arg() for Open Sans, as it causes a fatal error when script concatenation is used. See #26063

[dimadin]

Sorry, guys! I haven't thought about this. Obviously src version had no problems when I tried.

[dimadin]

(cross posted from make/core comment)
I have coded a ​simple plugin that disables loading of Open Sans from Google's servers using feature introduced in [26376]. If you have any comments about it (including its name), please share and I'll submit it to repository in a few days.