message: catch ev arg so the disable stuff works
diff: @@ -121,7 +121,7 @@ module.exports = React.createClass({
  }
  },
  - _doSubmit: function() {
  + _doSubmit: function(ev) {
  let email = this.refs.email.value.trim();
  var promise = this.props.onRegisterClick({
  username: this.refs.username.value.trim() || this.props.guestUsername,
  