Im looking for a way to group the invoice lines by a certain field for OpenERP 7. I see some examples of passing a context with a group_by key for a one2many list, but it looks like thats for older versions. Does anyone know how to do this for v7?

I also noticed in the account invoice form view, that the field invoice_line is using a one2many_list widget. Does anyone know where I can find the code for the widget, so that I can see if the lines are being grouped by that? Thank you for your help