wvvw

ok, i think i found the solution.
It is pretty simple: I am just checking is POST[wt] is an array

so replace 76 line with following

if (is_array($_POST['wl']))
$this->context_options = array_merge( $this->context_options, $_POST['wl'] );
else
$this->context_options = array_merge( $this->context_options, array($_POST['wl']) );