diff --git a/addons/hr_evaluation/hr_evaluation.py b/addons/hr_evaluation/hr_evaluation.py
index b13e90cd627..eece0c7497e 100644
--- a/addons/hr_evaluation/hr_evaluation.py
+++ b/addons/hr_evaluation/hr_evaluation.py
@@ -291,6 +291,7 @@ survey_request()
 class hr_evaluation_interview(osv.osv):
     _name = 'hr.evaluation.interview'
     _inherits = {'survey.request': 'request_id'}
+    _inherit =  'mail.thread'
     _rec_name = 'request_id'
     _description = 'Appraisal Interview'
     _columns = {
diff --git a/addons/hr_holidays/hr_holidays.py b/addons/hr_holidays/hr_holidays.py
index f315f3d4ef3..419b1bb8335 100644
--- a/addons/hr_holidays/hr_holidays.py
+++ b/addons/hr_holidays/hr_holidays.py
@@ -113,6 +113,13 @@ class hr_holidays(osv.osv):
                 result[hol.id] = hol.number_of_days_temp
         return result
 
+    def _check_date(self, cr, uid, ids):
+        for holiday in self.browse(cr, uid, ids):
+            holiday_ids = self.search(cr, uid, [('date_from', '<=', holiday.date_to), ('date_to', '>=', holiday.date_from), ('employee_id', '=', holiday.employee_id.id), ('id', '<>', holiday.id)])
+            if holiday_ids:
+                return False
+        return True
+
     _columns = {
         'name': fields.char('Description', size=64),
         'state': fields.selection([('draft', 'To Submit'), ('cancel', 'Cancelled'),('confirm', 'To Approve'), ('refuse', 'Refused'), ('validate1', 'Second Approval'), ('validate', 'Approved')],
@@ -146,6 +153,10 @@ class hr_holidays(osv.osv):
         'user_id': lambda obj, cr, uid, context: uid,
         'holiday_type': 'employee'
     }
+    _constraints = [
+        (_check_date, 'You can not have 2 leaves that overlaps on same day!', ['date_from','date_to']),
+    ] 
+    
     _sql_constraints = [
         ('type_value', "CHECK( (holiday_type='employee' AND employee_id IS NOT NULL) or (holiday_type='category' AND category_id IS NOT NULL))", "The employee or employee category of this request is missing."),
         ('date_check2', "CHECK ( (type='add') OR (date_from <= date_to))", "The start date must be anterior to the end date."),
@@ -252,6 +263,13 @@ class hr_holidays(osv.osv):
             result['value']['number_of_days_temp'] = 0
 
         return result
+    
+    def write(self, cr, uid, ids, vals, context=None):
+        check_fnct = self.pool.get('hr.holidays.status').check_access_rights
+        for  holiday in self.browse(cr, uid, ids, context=context):
+            if holiday.state in ('validate','validate1') and not check_fnct(cr, uid, 'write', raise_exception=False):
+                raise osv.except_osv(_('Warning!'),_('You cannot modify a leave request that has been approved. Contact a human resource manager.'))
+        return super(hr_holidays, self).write(cr, uid, ids, vals, context=context)
 
     def set_to_draft(self, cr, uid, ids, context=None):
         self.write(cr, uid, ids, {
diff --git a/addons/hr_holidays/hr_holidays_demo.xml b/addons/hr_holidays/hr_holidays_demo.xml
index 4c9d18683c7..accf8c26935 100644
--- a/addons/hr_holidays/hr_holidays_demo.xml
+++ b/addons/hr_holidays/hr_holidays_demo.xml
@@ -34,8 +34,8 @@
     <record model="hr.holidays" id="hr_holidays_employee1_vc">
       <field name="name">Summer Vacation</field>
       <field name="holiday_status_id" ref="holiday_status_unpaid"/>
-      <field eval="time.strftime('%Y-%m-20')" name="date_from"/>
-      <field eval="time.strftime('%Y-%m-22')" name="date_to"/>
+      <field eval="time.strftime('%Y-%m-23')" name="date_from"/>
+      <field eval="time.strftime('%Y-%m-25')" name="date_to"/>
       <field name="type">add</field>
       <field name="state">draft</field>
       <field name="number_of_days_temp">7</field>
@@ -45,8 +45,8 @@
     <record model="hr.holidays" id="hr_holidays_employee1_int_tour">
       <field name="name">International Tour</field>
       <field name="holiday_status_id" ref="holiday_status_comp"/>
-      <field eval="time.strftime('%Y-%m-20')" name="date_from"/>
-      <field eval="time.strftime('%Y-%m-22')" name="date_to"/>
+      <field eval="time.strftime('%Y-%m-26')" name="date_from"/>
+      <field eval="time.strftime('%Y-%m-28')" name="date_to"/>
       <field name="type">add</field>
       <field name="number_of_days_temp">7</field>
       <field name="employee_id" ref="hr.employee_fp"/>
diff --git a/addons/mail/__init__.py b/addons/mail/__init__.py
index aea7ee62cbc..003369be38f 100644
--- a/addons/mail/__init__.py
+++ b/addons/mail/__init__.py
@@ -22,12 +22,12 @@
 import mail_message_subtype
 import mail_alias
 import mail_followers
+import mail_favorite
 import mail_message
 import mail_mail
 import mail_thread
 import mail_group
 import mail_vote
-import mail_favorite
 import res_partner
 import res_users
 import report