diff --git a/addons/point_of_sale/pos.py b/addons/point_of_sale/pos.py
index 954110d2036..d29482db4de 100644
--- a/addons/point_of_sale/pos.py
+++ b/addons/point_of_sale/pos.py
@@ -44,7 +44,17 @@ class pos_order(osv.osv):
     _order = "date_order, create_date desc"
     _order = "date_order desc"
 
-    wf_service = netsvc.LocalService("workflow")
+    def unlink(self, cr, uid, ids, context={}):
+        for rec in self.browse(cr, uid, ids, context=context):
+            if rec.state<>'draft':
+                raise osv.except_osv(_('Invalid action !'), _('Cannot delete a point of sale which is already confirmed !'))
+        return super(pos_order, self).unlink(cr, uid, ids, context=context)
+
+    def onchange_partner_pricelist(self, cr, uid, ids, part, context={}):
+        if not part:
+            return {}
+        pricelist = self.pool.get('res.partner').browse(cr, uid, part).property_product_pricelist.id 
+        return {'value':{'pricelist_id': pricelist}}
 
     def _amount_total(self, cr, uid, ids, field_name, arg, context):
         id_set = ",".join(map(str, ids))
@@ -340,7 +350,8 @@ class pos_order(osv.osv):
                         'location_dest_id': stock_dest_id,
                     })
 
-            self.wf_service.trg_validate(uid, 'stock.picking',
+            wf_service = netsvc.LocalService("workflow")
+            wf_service.trg_validate(uid, 'stock.picking',
                     picking_id, 'button_confirm', cr)
             self.pool.get('stock.picking').force_assign(cr,
                     uid, [picking_id], context)
@@ -375,7 +386,8 @@ class pos_order(osv.osv):
             clone_id = picking_obj.copy(
                 cr, uid, order.last_out_picking.id, {'type': 'in'})
             # Confirm the picking
-            self.wf_service.trg_validate(uid, 'stock.picking',
+            wf_service = netsvc.LocalService("workflow")
+            wf_service.trg_validate(uid, 'stock.picking',
                 clone_id, 'button_confirm', cr)
             clone_list.append(clone_id)
             # Remove the ref to last picking and delete the payments
@@ -409,8 +421,9 @@ class pos_order(osv.osv):
             'amount': amount,
             })
 
-        self.wf_service.trg_validate(uid, 'pos.order', order_id, 'payment', cr)
-        self.wf_service.trg_write(uid, 'pos.order', order_id, cr)
+        wf_service = netsvc.LocalService("workflow")
+        wf_service.trg_validate(uid, 'pos.order', order_id, 'payment', cr)
+        wf_service.trg_write(uid, 'pos.order', order_id, cr)
         return payment_id
 
     def add_product(self, cr, uid, order_id, product_id, qty, context=None):
@@ -430,7 +443,8 @@ class pos_order(osv.osv):
             'qty': qty,
             'price_unit': price,
             })
-        self.wf_service.trg_write(uid, 'pos.order', order_id, cr)
+        wf_service = netsvc.LocalService("workflow")
+        wf_service.trg_write(uid, 'pos.order', order_id, cr)
 
         return order_line_id
 
@@ -504,7 +518,8 @@ class pos_order(osv.osv):
                 inv_line_ref.create(cr, uid, inv_line, context)
 
         for i in inv_ids:
-            self.wf_service.trg_validate(uid, 'account.invoice', i, 'invoice_open', cr)
+            wf_service = netsvc.LocalService("workflow")
+            wf_service.trg_validate(uid, 'account.invoice', i, 'invoice_open', cr)
         return inv_ids
 
     def create_account_move(self, cr, uid, ids, context=None):
@@ -809,7 +824,7 @@ class pos_payment(osv.osv):
 
     _columns = {
         'name': fields.char('Description', size=64),
-        'order_id': fields.many2one('pos.order', 'Order Ref', required=True),
+        'order_id': fields.many2one('pos.order', 'Order Ref', required=True, ondelete='cascade'),
         'journal_id': fields.many2one('account.journal', "Journal", required=True),
         'amount': fields.float('Amount', required=True),
     }
diff --git a/addons/point_of_sale/pos_view.xml b/addons/point_of_sale/pos_view.xml
index b9fe90df9f1..4c6510f4abb 100644
--- a/addons/point_of_sale/pos_view.xml
+++ b/addons/point_of_sale/pos_view.xml
@@ -80,7 +80,7 @@
                             <separator string="Invoicing" colspan="4"/>
                             <field name="nb_print"/>
                             <newline/>
-                            <field name="partner_id" />
+                            <field name="partner_id" on_change="onchange_partner_pricelist(partner_id)"/>
                             <newline/>
                             <field name="invoice_id"/>
                             <label/>