var selected;
            
$(document).ready(function () {
            
  selected = $(".positionbox div:first");
  selected.show();
  _do_arrows();
                
                
$('#forward').bind('click', function(){
  selected.hide();
  selected = selected.next();
  selected.show();
  _do_arrows();
  });
$('#back').bind('click', function(){
  selected.hide();
  selected = selected.prev();
  selected.show();
  _do_arrows();
  });
  });
            
            
function _do_arrows() {
  if (selected.next().get().length > 0) {
$('#forward').show();
  } else {
$('#forward').hide();
  }
  if (selected.prev().get().length > 0) {
$('#back').show();
  } else {
$('#back').hide();
  }
  }