DatePicker buttons are disabled

[SimonF]

With the new pre release Version 13.1 its not possible anymore to navigate throw the datePicker calendar, if the value is before 2013. The Buttons are disabled. This was possible with the 13.0 Version.

I think thats a bug, because it should be possible to navigate in the calendar if the value is already before 2013

isc.DynamicForm.create(
{
"ID":"personForm_39",
"width": 350,
"groupTitle":"Persönliche Daten",
"groupBorderCSS":"1px solid #BBBBBB",
"margin":"5px",
"padding":4,
"hideUsingDisplayNone":false,
"autoFocus":true,
"selectOnFocus":true,
"canEdit":true,
"readOnlyDisplay":"static",
"fields": [{
"ID":"dateOfBirthField_39",
"name":"dateOfBirthField_39",
"title":"Geburtsdatum",
"type":"date",
"textAlign":"left",
"useTextField":true,}],
"values": {"dateOfBirthField_39":"14.01.1970"}
})