Getting a "nested" setting

plugin_settings.rhtml

<p>
    <label><%= l(:setting_collapse_menustab) %></label>
    <%= check_box_tag 'settings[show_menus_tab]', 1, Setting.plugin_redmine_collapse['show_menus_tab'] == '1', :onclick=>"Element.toggle('menustab_content'); return true;" %><%= hidden_field_tag 'settings[show_menus_tab]', 0 %>
</p>
    
<div id="menustab_content" <%= Setting.plugin_redmine_collapse['show_menus_tab'] == '1' ? '' : 'style="display:none"' %>>
    <p>
        <label><%= l(:setting_collapse_pmtab) %></label>
        <%= select_tag 'settings[show_projectmenu_tab]', options_for_select( [[l(:general_text_No), "0"], [l(:general_text_Yes), "1"]], @settings ['show_projectmenu_tab'] ) %>
    </p>
</div>