diff --git a/modoboa/admin/forms.py b/modoboa/admin/forms.py
index 3ba571cdd..d9dbd52c5 100644
--- a/modoboa/admin/forms.py
+++ b/modoboa/admin/forms.py
@@ -125,7 +125,8 @@ class DomainForm(TabForms):
         if "instances" in kwargs:
             cbargs += [kwargs["instances"]["general"]]
         self.forms += events.raiseQueryEvent("ExtraDomainForm", *cbargs)
-
+        if not self.forms:
+            self.active_id = "admins"
         super(DomainForm, self).__init__(*args, **kwargs)
 
     def save(self, user):
diff --git a/modoboa/admin/models.py b/modoboa/admin/models.py
index 92aadc4d6..383e243d3 100644
--- a/modoboa/admin/models.py
+++ b/modoboa/admin/models.py
@@ -719,6 +719,11 @@ class Mailbox(DatesAware):
             raise AdminError(_("Failed to remove mailbox: %s" % output))
 
     def set_quota(self, value, override_domain=False):
+        """Set or update quota's value for this mailbox.
+
+        :param integer value: the quota's value
+        :param bool override_domain: allow to override domain's limit or not
+        """
         if value is None:
             self.quota = self.domain.quota
         elif int(value) > self.domain.quota and not override_domain:
diff --git a/modoboa/admin/templates/admin/editdomainform.html b/modoboa/admin/templates/admin/editdomainform.html
index e2987715d..24c731769 100644
--- a/modoboa/admin/templates/admin/editdomainform.html
+++ b/modoboa/admin/templates/admin/editdomainform.html
@@ -1,18 +1,24 @@
 {% extends "common/tabforms.html" %}{% load i18n libextras admin_extras %}
 {% block extratabs %}
-  <li><a href="#admins" data-toggle="tab">{% trans "Administrators" %}</a></li>
-  <li><a href="#misc" data-toggle="tab">{% trans "Miscellaneous" %}</a></li>
+  <li class="{% if tabs.active_id == 'admins' %}active{% endif %}">
+    <a href="#admins" data-toggle="tab">{% trans "Administrators" %}</a>
+  </li>
+  <li class="{% if tabs.active_id == 'misc' %}active{% endif %}">
+    <a href="#misc" data-toggle="tab">{% trans "Miscellaneous" %}</a>
+  </li>
 {% endblock %}
 {% block extratabs_content %}
-<div class="tab-pane" id="admins">{% if domadmins %}
+<div class="tab-pane{% if tabs.active_id == 'admins' %} active{% endif %}" id="admins">{% if domadmins %}
   <table id="domadmins" class="table table-condensed">
     <tr><th>{% trans "Username" %}</th><th>{% trans "Name" %}</th><th></th></tr>
     {% for da in domadmins %}<tr>
-      <td>{{ da.username }}</td><td>{{ da.fullname }}</td><td name="actions">{% domadmin_actions da.id domain.id %}</td>
+      <td>{{ da.username }}</td>
+      <td>{{ da.fullname }}</td>
+      <td name="actions">{% if perms.admin.change_domain%}{% domadmin_actions da.id domain.id %}{% endif %}</td>
     </tr>{% endfor %}
   </table>{% else %}<div class="alert alert-info">{% trans "No domain administrator defined" %}</div>{% endif %}
 </div>
-<div class="tab-pane" id="misc">
+<div class="tab-pane{% if tabs.active_id == 'misc' %} active{% endif %}" id="misc">
   <div class="row"><span class="title">{% trans "Creation date" %}</span><span>{{ domain.creation }}</span></div>
   <div class="row"><span class="title">{% trans "Last modification date" %}</span><span>{{ domain.last_modification }}</span></div>
   <div class="row"><span class="title">{% trans "Domain aliases" %}</span><span>{{ domain.domainalias_count }}</span></div>
diff --git a/modoboa/lib/formutils.py b/modoboa/lib/formutils.py
index 83ff8a6ee..64a428e8e 100644
--- a/modoboa/lib/formutils.py
+++ b/modoboa/lib/formutils.py
@@ -85,22 +85,23 @@ class TabForms(object):
         for fd in self.forms:
             args = []
             kwargs = {}
-            if fd.has_key("new_args"):
+            if "new_args" in fd:
                 args += fd["new_args"]
-            if data:
+            if data is not None:
                 args.append(data)
-            if instances:
+            if instances is not None:
                 if hasattr(self, "check_%s" % fd["id"]):
                     if not getattr(self, "check_%s" % fd["id"])(instances[fd["id"]]):
                         to_remove += [fd]
                         continue
                 kwargs["instance"] = instances[fd["id"]]
-            if classes and classes.has_key(fd["id"]):
+            if classes is not None and fd["id"] in classes:
                 fd["instance"] = classes[fd["id"]](*args, **kwargs)
             else:
                 fd["instance"] = fd["cls"](*args, **kwargs)
         map(lambda fd: self.forms.remove(fd), to_remove)
-        self.active_id = self.forms[0]["id"]
+        if self.forms:
+            self.active_id = self.forms[0]["id"]
 
     def _before_is_valid(self, form):
         return True