anchor.diff:  <script>
  +  var addItemKeyCode = 122; // F11
  +  var removeItemKeyCode = 123; // F12
  +  
     var newAgentSlect2options = {
       multiple: false,
       minimumInputLength: 1,
  
positive.code:       + '<td><input type="button" value="+" onClick="ItemField_contributor.add();" /></td>'
        + '<td><input type="button" value="-" onClick="ItemField_contributor.remove(__count__);" /></td>',
      add : function () {
        var $new_field = $("<tr/>").attr("id", "CF" + this.currentNumber);
  
        var $clone = $('input[name="contributor_agent_ids[0]"]').clone();
        $clone.attr('name','contributor_agent_ids[' + this.currentNumber + ']');
  
negative.code:       this.currentNumber += 1;
      },
      remove : function (div_num) {
        var field = document.getElementById('RF' + div_num);
        if(field != null){ field.parentNode.removeChild(field); }
      }
    }
  