Payment dialog proposal

[Geert Janssens]

On Monday 7 December 2009, Derek Atkins wrote:
> Looks fine to me.
>
> Also, if there is some way you can signal that the Invoice/Bill
> selection is *optional* that would be good, too.
>
> -derek

I could add a tooltip to the corresponding widgets ? Problem is, the "owner" 
can be Vendor or Customer, and "invoice" can become Invoice or Bill. So I'm 
unsure I can come up with a wording that is independent of this, unless 
something like this will do for now:

  The Invoice/Bill to assign this payment to. Note that is field is optional.
  If you leave it blank, GnuCash will automatically assign the payment to the
  first unpaid invoice/bill for this customer/vendor.

Geert