Jquery Ui Datepicker month/year dropdown is not working in popup in latest firefox

Somehow my jQuery UI Datepicker Month/Year Dropdown not working in any popup in latest firefox .

When I click on Month or Year Dropdown, the options list doesn't appears.

Here is my Popup & Datepicker Code:

$( "#dialog-form" ).dialog({
    modal: true
});

$("#datepicker").datepicker({
    changeMonth: true,
    changeYear: true
});

I prepared a demo on JSfiddle too:

http://jsfiddle.net/469zV/2/

This is because the modal enforces focus on itself. Here is a solution for this as mentioned here . Add the below script to your js file. That's it.

jsfiddle: http://jsfiddle.net/surjithctly/93eTU/16/

Ref: Twitter bootstrap multiple modal error

// Since confModal is essentially a nested modal it's enforceFocus method
// must be no-op'd or the following error results 
// "Uncaught RangeError: Maximum call stack size exceeded"
// But then when the nested modal is hidden we reset modal.enforceFocus
var enforceModalFocusFn = $.fn.modal.Constructor.prototype.enforceFocus;

$.fn.modal.Constructor.prototype.enforceFocus = function() {};

$confModal.on('hidden', function() {
    $.fn.modal.Constructor.prototype.enforceFocus = enforceModalFocusFn;
});

$confModal.modal({ backdrop : false });

For Bootstrap 4:

replace : $.fn.modal.Constructor.prototype.enforceFocus
By: $.fn.modal.Constructor.prototype._enforceFocus