Solution:
In tinymce init:
relative_urls:false,
external_filemanager_path:"/BAD/filemanager/",
filemanager_title:"Filemanager" ,
external_plugins: { "filemanager" : "/BAD/filemanager/plugin.min.js"}
and in config.php
$base_url="http://localhost";
$upload_dir = '/BAD/source/';
$current_path = '../source/';
$thumbs_base_path = '../thumbs/';