kotti/templates/messages.pt
<div id="messages" class="${request.is_xhr and 'ajax-replace' or ''}">
<div tal:repeat="queue ('info', 'success', 'error', 'warning', '')" tal:omit-tag="">
<div tal:define="messages request.session.pop_flash(queue)"
tal:condition="messages"
tal:repeat="message messages"
class="alert-dismissable alert alert-${'danger' if queue == 'error' else queue}">
<button type="button" class="close" data-dismiss="alert"
aria-hidden="true">×</button>
${message}
</div>
</div>
</div>