ui: 修复problem_create页面添加标签无效的问题

packages/ui-default/templates/partials/footer.html

@@ -57,6 +57,13 @@
               <li class="menu__item"><a class="menu__link" href="{{ url('switch_language', lang=k) }}">{{ v }}</a></li>
             {%- endfor -%}
             </ol>
+            <li class="footer__extra-link-item" data-dropdown-target="#menu-footer-theme">
+            <span><span class="icon icon-global"></span> Theme <span class="icon icon-expand_less"></span></span>
+            <ol class="dropdown-target menu" id="menu-footer-theme">
+            {%- for k in UiContext.themes -%}
+              <li class="menu__item"><a class="menu__link" href="{{ url('set_theme', theme=k) }}">{{ k }}</a></li>
+            {%- endfor -%}
+            </ol>
           </li>
         </ol>
       </div>