code: function(){
        var self = this;
        todo.selected_priority = this.value;
        $(todo.all_pbs).each(function(i, pb){
          if (pb != self){
            pb.deselect();
          }
        });
        this.selected = true;
        $(this.button).css({
          'background-position': '0px -50px'
        });
        $('#new_item').css({
          'background-color': self.color
        });
      }
docs: Give the priority button a couple methods for selection/deselection (works much like a radio button)