group by date have not same behaviour on list or graph view

[Antoine]

Problem meet in openerp 6.1 with web or gtk interface.
For example, I'm on account invoice in search/tree view, I make a group by invoice date.
In this first view, I can see a group by month. Then, when I go in graph view, group by date (previously by month) become group by day.

In same bug type, we can see a ressource in list view with a group by month and order by month number. When you watch them in graph view, month is order by month name. ( Bug 886519 )