    function add() {
        var to = opener.document.getElementById('msgto');
        var from = document.getElementsByName('users');

        var add = new Array();
        var j = 0;

        if(from.length > 0) {
            for (var i=0; i<from.length; i++) {
                if(from[i].checked == 1) {
                    add[j++] = from[i].value;
                }
            }
        }

        if(to.value != '') {
            old = to.value.split(', ');
            for(i=0;i<old.length;i++) {
                for(j=0;j<add.length;j++) {
                    if(add[j] == old[i]) {
                        add.splice(j,1);
                        break;
                    }
                }
            }
            if(add.length > 0) {
                to.value += ', '+add.join(', ');
            }
        } else {
            to.value = add.join(', ');
        }

        opener.aBookOpen = false;
        self.close();
    }