diff --git a/__init__.py b/__init__.py
index 8938926..983a242 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,17 +1,17 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
 from trytond.pool import Pool
-from .drawing import *
-from .bom import *
-from .production import *
+from . import drawing
+from . import bom
+from . import production
 
 
 def register():
     Pool.register(
-        Drawing,
-        DrawingPosition,
-        BOM,
-        BOMDrawingLine,
-        Production,
-        ProductionDrawingLine,
+        drawing.Drawing,
+        drawing.DrawingPosition,
+        bom.BOM,
+        bom.BOMDrawingLine,
+        production.Production,
+        production.ProductionDrawingLine,
         module='production_drawing', type_='model')
diff --git a/bom.xml b/bom.xml
index 55ad28c..fbdf1d9 100644
--- a/bom.xml
+++ b/bom.xml
@@ -45,13 +45,11 @@
         </record>
         <record model="ir.ui.view" id="bom_view_form">
             <field name="model">production.bom</field>
-            <field name="type">form</field>
             <field name="inherit" ref="production.bom_view_form"/>
             <field name="name">bom_form</field>
         </record>
         <record model="ir.ui.view" id="bom_view_list">
             <field name="model">production.bom</field>
-            <field name="type">tree</field>
             <field name="inherit" ref="production.bom_view_list"/>
             <field name="name">bom_list</field>
         </record>
diff --git a/production.py b/production.py
index e0a0015..ea26d6d 100644
--- a/production.py
+++ b/production.py
@@ -25,13 +25,11 @@ class Production:
         cls.bom.on_change.add('drawing_lines')
 
     def on_change_bom(self):
-        res = super(Production, self).on_change_bom()
-        res['drawing'] = self.on_change_with_drawing()
+        super(Production, self).on_change_bom()
         self.drawing = (self.bom.drawing.id if self.bom and self.bom.drawing
             else None)
-        res['drawing_image'] = self.on_change_with_drawing_image()
-        res['drawing_lines'] = self.on_change_with_drawing_lines()
-        return res
+        self.on_change_with_drawing_image()
+        self.on_change_with_drawing_lines()
 
     @fields.depends('drawing')
     def on_change_with_drawing_lines(self):
@@ -66,8 +64,8 @@ class Production:
             production.drawing_lines = []
             for line in production.bom.drawing_lines:
                 production.drawing_lines.append(Line(
-                        position = line.position,
-                        product = line.product,
+                        position=line.position,
+                        product=line.product,
                         ))
         return production
 
diff --git a/production.xml b/production.xml
index 9330e30..8d5119d 100644
--- a/production.xml
+++ b/production.xml
@@ -43,7 +43,6 @@
 
         <record model="ir.ui.view" id="production_view_form">
             <field name="model">production</field>
-            <field name="type">form</field>
             <field name="inherit" ref="production.production_view_form"/>
             <field name="name">production_form</field>
         </record>
diff --git a/tryton.cfg b/tryton.cfg
index 7c446ce..6197be6 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -1,5 +1,5 @@
 [tryton]
-version=3.4.0
+version=4.0
 depends:
     production
 extras_depend:
diff --git a/view/bom_form.xml b/view/bom_form.xml
index e36a0bc..bad8764 100644
--- a/view/bom_form.xml
+++ b/view/bom_form.xml
@@ -12,7 +12,7 @@
                 <field name="drawing_lines" colspan="4" yexpand="1"/>
             </group>
             <group col="1" id="drawing_image" yexpand="1">
-                <field name="drawing_image" widget="image" img_height="300" img_width="200"/>
+                <field name="drawing_image" widget="image"/>
             </group>
         </page>
     </xpath>
diff --git a/view/drawing_form.xml b/view/drawing_form.xml
index 598ea48..842efe0 100644
--- a/view/drawing_form.xml
+++ b/view/drawing_form.xml
@@ -11,7 +11,7 @@
             <field name="positions" colspan="4" yexpand="1"/>
         </group>
         <group col="1" id="image" yexpand="1">
-            <field name="image" widget="image" img_height="300" img_width="200"/>
+            <field name="image" widget="image"/>
         </group>
     </group>
 </form>
diff --git a/view/production_form.xml b/view/production_form.xml
index 50a585d..8c70593 100644
--- a/view/production_form.xml
+++ b/view/production_form.xml
@@ -10,7 +10,7 @@ this repository contains the full copyright notices and license terms. -->
                 <field name="drawing_lines" colspan="4" yexpand="1"/>
             </group>
             <group col="1" id="drawing_image" yexpand="1">
-                <field name="drawing_image" widget="image" img_height="300" img_width="200"/>
+                <field name="drawing_image" widget="image"/>
             </group>
         </page>
     </xpath>