http://code.google.com/p/zkspreadsheet/issues/detail?id=299

Reported by stephan....@apinso.com, Mar 10, 2011

1. set a date-value to cell by program
2. edit this cell

I would expect to have the date value and can edit it.
Instead I get a double value.
It doesn't matter if the date has a time or not.

german locale