For what it worst, I end up with writing function set_calendar which move calendar to right date
at start and each time when calendar is picked
$('#dd').datebox({
onSelect: function(date){
set_calendar(date.getFullYear(), date.getMonth(), date.getDate());
}
});
function set_calendar(y, m, d) {
var el = $('#dd').datebox('calendar');
el.calendar('moveTo', new Date(y, m, d));
}