app/views/shared/_multi_selection.html_checkbox.erb
<%= select_tag("#{form_field}_select[]", options_for_select(source.collect { |ff| [ff.send(field_show), ff.send(field_store)] }, selected.collect { |fs| fs.send(field_store) }),
{:multiple=>true, :id => "#{form_field}_select"}) %>
<%= hidden_field_tag form_field, selected.join(",") %>
<script>
$(<%= "#{form_field}_select" %>).multiselect({
//selectedList: 4
}).multiselectfilter();
</script>