Thank you very much!
I managed to find the bug and fix it, the fix will be included in the upcoming release. It was only present with very specific configurations only, it went under our radars.
I also corrected the custom code, the tabbing should now work. For reference, the correct code is:
add_action('wp_footer', 'asp_tab_trigger_right');
function asp_tab_trigger_right() {
?>
<script>
jQuery(function($){
$('input.orig').on('keydown', function(e){
var kc = e.which || e.keyCode;
if ( kc == 9 ) {
e.preventDefault();
var ev = new Event('keyup');
ev.which = 39;
this.dispatchEvent(ev);
}
});
});
</script>
<?php
}