redmine/app/views/groups/_new_users_modal.html.erb

<h3 class="title"><%= l(:label_user_new) %></h3>

<%= form_for(@group, :url => group_users_path(@group), :remote => true, :method => :post) do |f| %>
  <%= render :partial => 'new_users_form' %>
  <p class="buttons">
    <%= submit_tag l(:button_add) %>
    <%= link_to_function l(:button_cancel), "hideModal(this);" %>
  </p>
<% end %>