New Account wizard; when Startup Interest Period set to "To Date" the date might show as blank

In the Account Quotation form and New Account wizard, when the Startup Interest Period set to "On Date", the startup period to date might show as blank.

To recreate:

1. Enter a new Account.
2. Set the Startup Interest Period to "To Date".
3. Enter the To Date as the current date.
4. Change the Opening date onwards a few days.

At this point the To Date appears blank. Clicking up/down in the To Date does nothing. This is because the To Date is prior to the Opening Date and therefore is invalid.

This behaviour has been changed so the To Date retains an invalid date, but when clicking "Calculate" a message to this effect is shown.