var what_form_select = $$('#sort_options form select');
var what_form_button = $$('#sort_options form button')[0];
what_form_button.style.display = 'none';

for (var i = 0; i < what_form_select.length; i ++)
    what_form_select[i].addEvent('change', function() {$$('#sort_options form')[0].submit();});