TinyMCE popups within Magnific-Popup cannot take focus in iframe

[phanthai12]

Demo: https://fiddle.tiny.cloud/Xwhaab/1

I set _onFocusIn but it not work

$.magnificPopup.instance._onFocusIn = function(e) {
    // Do nothing if target element is input
    if( $(e.target).closest( '.tox-tinymce' ) ) {
        return true;
    }

  // Else call parent method
    $.magnificPopup.proto._onFocusIn.call(this,e);
};