I have a simple formatter than in version 3.X was working, but in version 4.X is not:
$.extend($.fn.datebox.defaults.formatter = function(date){return myDate(date)});
function pad(val,max) { var str=val.toString(); return str.length < max ? pad("0" + str, max) : str;}
function myDate(date){ var y = date.getFullYear(); var m = pad(date.getMonth()+1,2); var d = pad(date.getDate(),2); return y+'-'+m+'-'+d;}
If I use version 3.61, then the correct selected date is shown, if i use 4.1 then it returns today's date.