How to set the tooltip of datepicker cells of a datefield

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!

You need to configure the longDayFormat config on the picker.

I don't configure the date picker. I just configure a datefield on a form panel. But, because I don't see a different way, I tried it.

Code:

---

initComponent: function () {
        var me = this;

        var myDatefield = Ext.create('widget.datefield', {
            fieldLabel: 'Gültig ab',
            labelWidth: 80,
            startDay: 1, // Starttag der Woche ist Montag
            minValue: new Date()
        });

        var myDatepicker = myDatefield.getPicker(); //to get the datepicker of my form panels' datefield

        Ext.apply(myDatepicker, {
            longDayFormat: 'j. F Y' // dt. format als tooltip
        });

        Ext.applyIf(me, {
            items: [
                  // ... some form panel items
                  myDatefield,
                  // ... some form panel items

---

I did the following: On the initComponent-method of my form panel I first create the datefield, then I use the datefields' getPicker-method and configure the longDayFormat to 'j. F Y'. While debugging I can see the right format in the longDayFormat config, BUT on the view it's still in the false format ('F d, Y'). I don't know why? Could you please help. Perhaps it's a bug? We use ExtJs 4.1.1.

As remark:
We use the german localization-file (ext-lang-de.js). So on datefield/-picker the format, disabledDaysText, disabledDatesText, maxText, minText, dayNames, today-btn. text etc. has changed to the desired format, but the longDayFormat (should be 'j. F Y') and the startDay (should be Monday - 1) has not. Perhaps a bug?

Additionaly in my opinion the config-name 'longDayFormat' is not really describing, that this is config for a tooltip of the cells of the datepicker. Please add this to the docs. And it would be nice to configure the datepicker belonging to a datefield directly on the datefield.