Visual Editor not working.. Just another reason

My visual editor was blank (not working). The reason was found: I have WP options home and siteurl set to relative uri /wordpress instead of http://example.com/wordpress (since I have a complex system of sharing different tables between websites).

There are different ways to make it work. I’ve chosen to make a with a very simple plugin:

add_filter('includes_url', 'my_full_includes_url', 10, 2);
function my_full_includes_url($url, $path)
{
    if ($path == 'js/tinymce' && !empty($url) && substr($url, 0, 1) == '/' && isset($_SERVER['HTTP_HOST']))
        $url = 'http://' . $_SERVER['HTTP_HOST'] . $url;
    return $url;
}

That’s it. Works for the latest 3.4.2. If you are in 2014 having problems with WP 4.5.7, please check setting the TinyMCE base url, something like

self::$baseurl = includes_url('js/tinymce');

in the _WP_Editors class, and add an action inside includes_url().