I have tested this item successfully on 60495d9

I have tested this item unsuccessfully on 60495d9

Video of my test and the issues that occured http://screencast.com/t/iTofr0wruP5H
Tested on Win10 XAMPP PHP 5.5 and Ubuntu 4.14 PHP 5.5.9

@JerryChr

have you cleaned all caches after patching?

@infograf768 yes and also tested in FireFox, Chrome and IE.
Just checked again and opened the console to see if there was anything in there - it gives me this:
Failed to load resource: the server responded with a status of 404 (Not Found)
Failed to load: media/editors/tinymce/plugins/jdragdrop/plugin.min.js in tinymce.min.js:4

Failed to load: media/editors/tinymce/plugins/jdragdrop/plugin.min.js in tinymce.min.js:4

is the culprit as this is in 3.5.0-dev/staging

I suggest you install a new staging ( https://github.com/joomla/joomla-cms/archive/staging.zip ), then patchtester, then this PR

@infograf768 Of course.. Think I need to debug my sleepy brain today instead.
Works on staging - will mark it succesfull now.

I have tested this item successfully on 60495d9

RTC as 2 good tests

This PR has received new commits.

CC: @infograf768, @JerryChr

Just added the two lines from #8711, to test follow the test instructions on #8711

I have an issue here in multilingual sites with custom.css, which I never remarked before.

In multilanguage, this will give a confusing result as we have one Home per Content Language and one could choose a different template (not only style) per language.
This code returns Beez instead of protostar

            $db    = JFactory::getDbo();
            $query = $db->getQuery(true)
                ->select('template')
                ->from('#__template_styles')
                ->where('client_id=0 AND home=' . $db->quote('1'));

            $db->setQuery($query);
            try
            {
                $template = $db->loadResult();
            }

When we choose Beez as default template for Language All

My suggestions :
1. Modify the tip
2. Introduce the case of multilanguage by displaying an error if the field is not filled with a full url.

What do you think?

Note: concerning IPv6, it does not load the file here locally with MAMP, i.e. with an url of the type
http://[::1]:8888/trunkgitnew/
or
http://[0:0:0:0:0:0:0:1]:8888/trunkgitnew/

where joomla is installed in the trunkgitnew folder.
Source shows:

content_css : "http://[0:0:0:0:0:0:0:1]:8888/trunkgitnew/templates/system/css/editor.css",
            document_base_url : "http://[0:0:0:0:0:0:0:1]:8888/trunkgitnew/",

As that may be expected I can't test it good or wrong.

@infograf768 For the multilingual part I would say that a modified tooltip that will point to the default for all languages is good enough. Trying to sort it out otherwise will be tricky I guess, not in front of my pc to actually test it.
About the second IPv6 and custom css, I think I forgot to change to Juri::root(true) which worked in the other PR

Even after changing to JUri::root(true) here, it does not work although we have now a relative link (corrected slash). Example:

content_css : "/trunkgitnew/templates/system/css/editor.css",
            document_base_url : "http://[0:0:0:0:0:0:0:1]:8888/trunkgitnew/",

But this could be due to MAMP here.

By the way this needs another slash before templates as @Fedik rightfully suggested in the other PR. Should be:
$content_css = 'content_css : "' . JUri::root(true) . '/templates/' . $template . '/css/' . $content_css_custom . '",';
$content_css = 'content_css : "' . JUri::root(true) . '/templates/system/css/editor.css",';
$content_css = 'content_css : "' . JUri::root(true) . '/templates/' . $template . '/css/editor.css",';

@infograf768 what version of mamp are you using? (I'm on 3.5)

2.1.1

(anyway needs the slash ☺ )

This PR has received new commits.

CC: @infograf768, @JerryChr

@infograf768 ok done!

Milestone here has to be 3.5.0