diff --git a/account_usability/account.py b/account_usability/account.py
index c23564b..6d17a11 100644
--- a/account_usability/account.py
+++ b/account_usability/account.py
@@ -140,6 +140,36 @@ class AccountInvoice(models.Model):
                     attach.id, attach.name)
         logger.info('END fix customer invoice attachment filename')
 
+    # for report
+    def py3o_lines_layout(self):
+        self.ensure_one()
+        res = []
+        has_sections = False
+        subtotal = 0.0
+        sign = self.type == 'out_refund' and -1 or 1
+        for line in self.invoice_line_ids:
+            if line.display_type == 'line_section':
+                # insert line
+                if has_sections:
+                    res.append({'subtotal': subtotal})
+                subtotal = 0.0  # reset counter
+                has_sections = True
+            else:
+                if not line.display_type:
+                    subtotal += line.price_subtotal * sign
+            res.append({'line': line})
+        if has_sections:  # insert last subtotal line
+            res.append({'subtotal': subtotal})
+        # res:
+        # [
+        #    {'line': account_invoice_line(1) with display_type=='line_section'},
+        #    {'line': account_invoice_line(2) without display_type},
+        #    {'line': account_invoice_line(3) without display_type},
+        #    {'line': account_invoice_line(4) with display_type=='line_note'},
+        #    {'subtotal': 8932.23},
+        # ]
+        return res
+
 
 class AccountInvoiceLine(models.Model):
     _inherit = 'account.invoice.line'
diff --git a/purchase_usability/purchase.py b/purchase_usability/purchase.py
index 6676eea..ac42171 100644
--- a/purchase_usability/purchase.py
+++ b/purchase_usability/purchase.py
@@ -28,8 +28,8 @@ class PurchaseOrder(models.Model):
             order.delivery_partner_id = order.dest_address_id
 
     def print_order(self):
-        action = self.env['report'].get_action(
-            self, 'purchase.report_purchaseorder')
+        report = self.env.ref('purchase.action_report_purchase_order')
+        action = report.report_action(self)
         return action
 
     # Re-write native name_get() to use amount_untaxed instead of amount_total
diff --git a/sale_usability/account_invoice.py b/sale_usability/account_invoice.py
index a7d7acc..8b8316c 100644
--- a/sale_usability/account_invoice.py
+++ b/sale_usability/account_invoice.py
@@ -10,44 +10,6 @@ from collections import OrderedDict
 class AccountInvoice(models.Model):
     _inherit = 'account.invoice'
 
-    # for report (located in sale_usability and not account_usability
-    # because it uses layout categ defined in sale
-    # Method used in the sample invoice report available here:
-    # https://github.com/akretion/odoo-py3o-report-templates/tree/10.0/account_invoice_report_py3o
-    def py3o_lines_layout(self):
-        self.ensure_one()
-        res1 = OrderedDict()
-        #    {'categ(6)': {'lines': [l1, l2], 'subtotal': 23.32}}
-        for line in self.invoice_line_ids:
-            categ = line.layout_category_id
-            if categ in res1:
-                res1[categ]['lines'].append(line)
-                res1[categ]['subtotal'] += line.price_subtotal
-            else:
-                res1[categ] = {
-                    'lines': [line],
-                    'subtotal': line.price_subtotal}
-        res2 = []
-        if len(res1) == 1 and not res1.keys()[0]:
-            # No category at all
-            for line in res1.values()[0]['lines']:
-                res2.append({'line': line})
-        else:
-            for categ, ldict in res1.iteritems():
-                res2.append({'categ': categ})
-                for line in ldict['lines']:
-                    res2.append({'line': line})
-                if categ.subtotal:
-                    res2.append({'subtotal': ldict['subtotal']})
-        # res2:
-        # [
-        #    {'categ': categ(1)},
-        #    {'line': invoice_line(2)},
-        #    {'line': invoice_line(3)},
-        #    {'subtotal': 8932.23},
-        # ]
-        return res2
-
     def py3o_lines_layout_groupby_order(self, subtotal=True):
         # This method is an alternative to the method py3o_lines_layout()
         # defined above: you just have to change the call in the invoice