Reikia, kad multiselect plugine pasirinkimai atsidarytu i viršų, kai select elementas labai arti lango apačios.

var $window = $(window);
var $multiselect = $('.multiselect').multiselect({
   header: false,
   beforeopen: function(){
      if (($window.height() - ($('.ui-multiselect').offset().top - $window.scrollTop()) ) < 180){
         $multiselect.multiselect("option", {position: {
            my: 'left bottom',
            at: 'left top'
         });
      }else{
         $multiselect.multiselect("option", {position: {
            my: 'left top',
            at: 'left bottom'
         }});
      }
   }
});