I have a form with a datefield. The datepicker of the datefield has a tooltip on every cell, which shows the current date in the following format: 'F d, Y'

I need a different format: 'j. F Y'

I spend a lot of time in searching after this... Every tooltip from datepicker has a describing property, configurable on the datefield, except of what I am looking for. What I found out is that the format is corresponding to the 'longDayFormat'-config property from datepicker. But I can not set this on datefield.

So how can I set the tooltip of the cells of the datepicker from a form's datefield? Please help and thank's in advance!