minor fix

inventory.py

@@ -46,20 +46,26 @@ class Inventory(metaclass=PoolMeta):
     @classmethod
     def __setup__(cls):
         super(Inventory, cls).__setup__()
-        cls.state.selection.extend([('pre_count', 'Pre-count'), ])
+        cls.state.selection.extend([('pre_count', 'Pre-count'), ('checkup', 'Checkup')])
         cls._transitions |= set((
-                ('draft', 'pre_count'),
+                ('draft', 'checkup'),
+                ('checkup', 'draft'),
+                ('checkup', 'pre_count'),
                 ('pre_count', 'done'),
                 ('pre_count', 'draft'),
                 ('draft', 'cancelled'),
                 ))
         cls._buttons.update({
             'pre_count': {
+                'invisible': Eval('state') != 'checkup',
+                'depends': ['state'],
+                },
+            'checkup': {
                 'invisible': Eval('state') != 'draft',
                 'depends': ['state'],
                 },
             'draft': {
-                'invisible': Eval('state') != 'pre_count',
+                'invisible': ~Eval('state').in_(['pre_count', 'checkup']),
                 'depends': ['state'],
                 },
         })
@@ -70,6 +76,12 @@ class Inventory(metaclass=PoolMeta):
     def pre_count(cls, inventories):
         pass
 
+    @classmethod
+    @ModelView.button
+    @Workflow.transition('checkup')
+    def checkup(cls, inventories):
+        pass
+
     @classmethod
     @ModelView.button
     @Workflow.transition('draft')

view/inventory_form.xml

@@ -17,6 +17,7 @@ this repository contains the full copyright notices and license terms. -->
     <xpath
         expr="/form/group[@id='buttons']/button[@name='count']" position="after">
         <button name="draft" string="Draft"/>
+        <button name="checkup" string="Checkup"/>
         <button name="pre_count" string="Pre-count"/>
     </xpath>
     <xpath