Avoid strip specific attributes with TinyMce - tinymce

Question

I would like to add the following content
<label for="tab1">Product Name</label>
inside a long product description in Prestashop, but when I save the product the "for" attributes is stripped away from HTML code.
I did some research and I found that the editor is TinyMCE and so I tried to change the configuration by adding:
extended_valid_elements : "+#[class|name|id|for]",
inside TinyMCE init script but the result is the same. I am sure that I didn't use the cached version of old script because I disable the Chrome cache and checked that the javascript code was correct.
Do you have any idea?
Here it is the full configuration script:
default_config = {
selector: ".rte" ,
plugins : "colorpicker link image paste pagebreak table contextmenu filemanager table code media autoresize textcolor anchor",
browser_spellcheck : true,
toolbar1 : "code,|,bold,italic,underline,strikethrough,|,alignleft,aligncenter,alignright,alignfull,formatselect,|,blockquote,colorpicker,pasteword,|,bullist,numlist,|,outdent,indent,|,link,unlink,|,anchor,|,media,image",
toolbar2: "",
external_filemanager_path: ad+"/filemanager/",
filemanager_title: "File manager" ,
external_plugins: { "filemanager" : ad+"/filemanager/plugin.min.js"},
language: iso,
skin: "prestashop",
statusbar: false,
relative_urls : false,
convert_urls: false,
entity_encoding: "raw",
extended_valid_elements : "+#[class|name|id|for]",
valid_children : "+*[*]",
valid_elements:"*[*]",
menu: {
edit: {title: 'Edit', items: 'undo redo | cut copy paste | selectall'},
insert: {title: 'Insert', items: 'media image link | pagebreak'},
view: {title: 'View', items: 'visualaid'},
format: {title: 'Format', items: 'bold italic underline strikethrough superscript subscript | formats | removeformat'},
table: {title: 'Table', items: 'inserttable tableprops deletetable | cell row column'},
tools: {title: 'Tools', items: 'code'}
}
};

Answer 1

Have you tried to add to extended_valid_elements the tag and not the attribute? Like this:
extended_valid_elements : "label[for]"
It's a fault of HTMLPurifier library, if you have control of the content of the html disable from the backoffice.
Preferences -> General set to NO Use HTMLPurifier Library
If you don't want to disable the library, you have to edit in PrestaShop/tools/htmlpurifier/
Maybe it's more easy to override the purifyHTML() method of Tools class, and add the 'for' attribute for the label, adding this when instancing the library:
$config->set('HTML.AllowedAttributes', 'label.for');