add(userForm);
RequiredTextField userName = new RequiredTextField("userName",
new PropertyModel(this, "userName"));
userName.add(new PrincipalNameValidator());
userForm.add(userName);
TextField password = new PasswordTextField("password",
new PropertyModel(this, "password"));
userForm.add(password);
CheckBox changePassword = new CheckBox("checkpass",
new PropertyModel(this, "checkpass"));
userForm.add(changePassword);