context in form definition not being passed

I am sorry if this is in the wrong area (i.e not sure if it is a server or client issue).

This works in version 6.1 but not in version 7.0.

Putting a "context=" on a one2many or many2many in the form definition does not pass the context to the functional fields defined within it.

I have simplified this to a farcical example in an area that appears unchanged between the two revisions.

In stock/stock.py, I have added a functional field to stock.move:

    def _tff(self, cr, uid, ids, field_names, arg, context=None):
        return dict.fromkeys(ids, 0)

...

        'tff': fields.function(_tff, type='float', string='TFF'),

and in stock/stock_view.xml I have modified the inventory view as follows:

                    <page string="Posted Inventory">
                         <field name="move_ids" context="{'inventory_id':active_id}" >
                            <tree string="Stock Moves">
                                ....
                                ....
                                <field name='tff'/>
                            </tree>
                         </field>
                    </page>

If I debug the _tff method, in version 6.1 the context has the "inventory_id", but in version 7.0, it does not.