message: Clear userlist before appending entries from "getUsers" result.
  If the server is returning entries slower than the user is entering
  additional characters, the callback gets executed multiple times after,
  the list has been cleared - resulting in the same entries being appended
  multiple times.
diff: @@ -670,6 +670,7 @@ jsxc.gui = {
  if (val !== '') {
  jsxc.options.getUsers.call(this, val, function(list) {
  + $('#jsxc_userlist').empty();
  $.each(list || {}, function(uid, displayname) {
  var option = $('<option>');
  option.attr('data-username', uid);
  