first draft

app/Resources/views/default/_flash_messages.html.twig

@@ -0,0 +1,25 @@
+{#
+   This is a template fragment designed to be included in other templates
+   See http://symfony.com/doc/current/book/templating.html#including-other-templates
+
+   A common practice to better distinguish between templates and fragments is to
+   prefix fragments with an underscore. That's why this template is called
+   '_flash_messages.html.twig' instead of 'flash_messages.html.twig'
+#}
+
+{% if app.session.started and app.session.flashBag.peekAll is not empty %}
+    <div class="messages">
+        {% for type, messages in app.session.flashBag.all %}
+            {% for message in messages %}
+                {# Bootstrap alert, see http://getbootstrap.com/components/#alerts #}
+                <div class="alert alert-dismissible alert-{{ type }}" role="alert">
+                    <button type="button" class="close" data-dismiss="alert" aria-label="Close">
+                        <span aria-hidden="true">&times;</span>
+                    </button>
+
+                    {{ message|trans }}
+                </div>
+            {% endfor %}
+        {% endfor %}
+    </div>
+{% endif %}