Please read: http://code.google.com/p/tryton/wiki/HowtoContribute#Back_port

Looks like patch applies on 3.4 without conflicts

Shall it stay open until it has been fixed in the 3.4 branch too?

I would treat this as bug instead of feature.

I suggest review10851002 as the proper fix for this very annoying bug. Please consider including it in 3.4 point release.

All of them.

Which case is missing?

The patch proposed doesn't do at all what is describe here.

I agree. But if there is not any line, the date could be also the start period. So the date must be:
- the start period if there is no date and no last line
- the last line date if there is no date
- the start period if the date is outside the period

I think the date must be:
- the last line date if there is no date
- the start period if the date is outside the period

(trunk, 3.4, 3.2) It not possible to change the date in an account move, always is replaced by the date computed by on_change_with_date() method (the last one used in a move line of the same journal and period or the start of the period).

This behaviour does not allow introduce/create account moves in an specific date in the account move form. It can be only done in the account move line tree.

I suggest in on_change_with_date() method no compute the date if the field contains a date, adding:

        if date:
            return date