Include this script after you've included jQuery UI. You can include it inline, or put it in its own file.
edit: This hack fixes your issue for version 1.8.5 of jQuery UI. I have tested a number of usage cases in FF 3.6.10 and IE 8. It is entirely possible that this hack does not work under all possible circumstances. If I notice any, I'll probably try to fix them, but for now, it is provided as is.
I've thrown together a demo. Shows it's working with jQuery 1.8.4, too. Just to be clear... my solution is not a quick and dirty workaround, it's an actual fix of the bug in the datepicker code. It's so long, because it overwrites an original method (and thus contains the original code in its entirety). The fix itself is a change in just one line. But I've provided the fix as a script that can just be included without having to edit the original code at all, for convenience.
$.extend(
$.datepicker,
{
_generateHTML:
function(inst) {
if (!inst.dpuuid)
{
for(attr in window)
{
if(/^DP_jQuery_/.test(attr))
{
inst.dpuuid = attr.replace(/^DP_jQuery_([0-9]+)/, '$1');
}
}
}
var dpuuid = inst.dpuuid;
var today = new Date();
today = this._daylightSavingAdjust(
new Date(today.getFullYear(), today.getMonth(), today.getDate())); // clear time
var isRTL = this._get(inst, 'isRTL');
var showButtonPanel = this._get(inst, 'showButtonPanel');
var hideIfNoPrevNext = this._get(inst, 'hideIfNoPrevNext');
var navigationAsDateFormat = this._get(inst, 'navigationAsDateFormat');
var numMonths = this._getNumberOfMonths(inst);
var showCurrentAtPos = this._get(inst, 'showCurrentAtPos');
var stepMonths = this._get(inst, 'stepMonths');
var isMultiMonth = (numMonths[0] != 1 || numMonths[1] != 1);
var currentDate = this._daylightSavingAdjust((!inst.currentDay ? new Date(9999, 9, 9) :
new Date(inst.currentYear, inst.currentMonth, inst.currentDay)));
var minDate = this._getMinMaxDate(inst, 'min');
var maxDate = this._getMinMaxDate(inst, 'max');
var drawMonth = inst.drawMonth - showCurrentAtPos;
var drawYear = inst.drawYear;
if (drawMonth < 0) {
drawMonth += 12;
drawYear--;
}
if (maxDate) {
var maxDraw = this._daylightSavingAdjust(new Date(maxDate.getFullYear(),
maxDate.getMonth() - (numMonths[0] * numMonths[1]) + 1, maxDate.getDate()));
maxDraw = (minDate && maxDraw < minDate ? minDate : maxDraw);
while (this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1)) > maxDraw) {
drawMonth--;
if (drawMonth < 0) {
drawMonth = 11;
drawYear--;
}
}
}
inst.drawMonth = drawMonth;
inst.drawYear = drawYear;
var prevText = this._get(inst, 'prevText');
prevText = (!navigationAsDateFormat ? prevText : this.formatDate(prevText,
this._daylightSavingAdjust(new Date(drawYear, drawMonth - stepMonths, 1)),
this._getFormatConfig(inst)));
var prev = (this._canAdjustMonth(inst, -1, drawYear, drawMonth) ?
'<a class="ui-datepicker-prev ui-corner-all" onclick="DP_jQuery_' + dpuuid +
'.datepicker._adjustDate(\'#' + inst.id + '\', -' + stepMonths + ', \'M\');"' +
' title="' + prevText + '"><span class="ui-icon ui-icon-circle-triangle-' + ( isRTL ? 'e' : 'w') + '">' + prevText + '</span></a>' :
(hideIfNoPrevNext ? '' : '<a class="ui-datepicker-prev ui-corner-all ui-state-disabled" title="'+ prevText +'"><span class="ui-icon ui-icon-circle-triangle-' + ( isRTL ? 'e' : 'w') + '">' + prevText + '</span></a>'));
var nextText = this._get(inst, 'nextText');
nextText = (!navigationAsDateFormat ? nextText : this.formatDate(nextText,
this._daylightSavingAdjust(new Date(drawYear, drawMonth + stepMonths, 1)),
this._getFormatConfig(inst)));
var next = (this._canAdjustMonth(inst, +1, drawYear, drawMonth) ?
'<a class="ui-datepicker-next ui-corner-all" onclick="DP_jQuery_' + dpuuid +
'.datepicker._adjustDate(\'#' + inst.id + '\', +' + stepMonths + ', \'M\');"' +
' title="' + nextText + '"><span class="ui-icon ui-icon-circle-triangle-' + ( isRTL ? 'w' : 'e') + '">' + nextText + '</span></a>' :
(hideIfNoPrevNext ? '' : '<a class="ui-datepicker-next ui-corner-all ui-state-disabled" title="'+ nextText + '"><span class="ui-icon ui-icon-circle-triangle-' + ( isRTL ? 'w' : 'e') + '">' + nextText + '</span></a>'));
var currentText = this._get(inst, 'currentText');
var gotoDate = (this._get(inst, 'gotoCurrent') && inst.currentDay ? currentDate : today);
currentText = (!navigationAsDateFormat ? currentText :
this.formatDate(currentText, gotoDate, this._getFormatConfig(inst)));
var controls = (!inst.inline ? '<button type="button" class="ui-datepicker-close ui-state-default ui-priority-primary ui-corner-all" onclick="DP_jQuery_' + dpuuid +
'.datepicker._hideDatepicker();">' + this._get(inst, 'closeText') + '</button>' : '');
var buttonPanel = (showButtonPanel) ? '<div class="ui-datepicker-buttonpane ui-widget-content">' + (isRTL ? controls : '') +
(this._isInRange(inst, gotoDate) ? '<button type="button" class="ui-datepicker-current ui-state-default ui-priority-secondary ui-corner-all" onclick="DP_jQuery_' + dpuuid +
'.datepicker._gotoToday(\'#' + inst.id + '\');"' +
'>' + currentText + '</button>' : '') + (isRTL ? '' : controls) + '</div>' : '';
var firstDay = parseInt(this._get(inst, 'firstDay'),10);
firstDay = (isNaN(firstDay) ? 0 : firstDay);
var showWeek = this._get(inst, 'showWeek');
var dayNames = this._get(inst, 'dayNames');
var dayNamesShort = this._get(inst, 'dayNamesShort');
var dayNamesMin = this._get(inst, 'dayNamesMin');
var monthNames = this._get(inst, 'monthNames');
var monthNamesShort = this._get(inst, 'monthNamesShort');
var beforeShowDay = this._get(inst, 'beforeShowDay');
var showOtherMonths = this._get(inst, 'showOtherMonths');
var selectOtherMonths = this._get(inst, 'selectOtherMonths');
var calculateWeek = this._get(inst, 'calculateWeek') || this.iso8601Week;
var defaultDate = this._getDefaultDate(inst);
var html = '';
for (var row = 0; row < numMonths[0]; row++) {
var group = '';
for (var col = 0; col < numMonths[1]; col++) {
var selectedDate = this._daylightSavingAdjust(new Date(inst.currentYear, inst.currentMonth, inst.selectedDay));
var cornerClass = ' ui-corner-all';
var calender = '';
if (isMultiMonth) {
calender += '<div class="ui-datepicker-group';
if (numMonths[1] > 1)
switch (col) {
case 0: calender += ' ui-datepicker-group-first';
cornerClass = ' ui-corner-' + (isRTL ? 'right' : 'left'); break;
case numMonths[1]-1: calender += ' ui-datepicker-group-last';
cornerClass = ' ui-corner-' + (isRTL ? 'left' : 'right'); break;
default: calender += ' ui-datepicker-group-middle'; cornerClass = ''; break;
}
calender += '">';
}
calender += '<div class="ui-datepicker-header ui-widget-header ui-helper-clearfix' + cornerClass + '">' +
(/all|left/.test(cornerClass) && row == 0 ? (isRTL ? next : prev) : '') +
(/all|right/.test(cornerClass) && row == 0 ? (isRTL ? prev : next) : '') +
this._generateMonthYearHeader(inst, drawMonth, drawYear, minDate, maxDate,
row > 0 || col > 0, monthNames, monthNamesShort) + // draw month headers
'</div><table class="ui-datepicker-calendar"><thead>' +
'<tr>';
var thead = (showWeek ? '<th class="ui-datepicker-week-col">' + this._get(inst, 'weekHeader') + '</th>' : '');
for (var dow = 0; dow < 7; dow++) { // days of the week
var day = (dow + firstDay) % 7;
thead += '<th' + ((dow + firstDay + 6) % 7 >= 5 ? ' class="ui-datepicker-week-end"' : '') + '>' +
'<span title="' + dayNames[day] + '">' + dayNamesMin[day] + '</span></th>';
}
calender += thead + '</tr></thead><tbody>';
var daysInMonth = this._getDaysInMonth(drawYear, drawMonth);
if (drawYear == inst.selectedYear && drawMonth == inst.selectedMonth)
inst.selectedDay = Math.min(inst.selectedDay, daysInMonth);
var leadDays = (this._getFirstDayOfMonth(drawYear, drawMonth) - firstDay + 7) % 7;
var numRows = (isMultiMonth ? 6 : Math.ceil((leadDays + daysInMonth) / 7)); // calculate the number of rows to generate
var printDate = this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1 - leadDays));
for (var dRow = 0; dRow < numRows; dRow++) { // create date picker rows
calender += '<tr>';
var tbody = (!showWeek ? '' : '<td class="ui-datepicker-week-col">' +
this._get(inst, 'calculateWeek')(printDate) + '</td>');
for (var dow = 0; dow < 7; dow++) { // create date picker days
var daySettings = (beforeShowDay ?
beforeShowDay.apply((inst.input ? inst.input[0] : null), [printDate]) : [true, '']);
var otherMonth = (printDate.getMonth() != drawMonth);
var unselectable = (otherMonth && !selectOtherMonths) || !daySettings[0] ||
(minDate && printDate < minDate) || (maxDate && printDate > maxDate);
tbody += '<td class="' +
((dow + firstDay + 6) % 7 >= 5 ? ' ui-datepicker-week-end' : '') + // highlight weekends
(otherMonth ? ' ui-datepicker-other-month' : '') + // highlight days from other months
((printDate.getTime() == selectedDate.getTime() && drawMonth == inst.selectedMonth && inst._keyEvent) || // user pressed key
(defaultDate.getTime() == printDate.getTime() && defaultDate.getTime() == selectedDate.getTime()) ?
// or defaultDate is current printedDate and defaultDate is selectedDate
' ' + this._dayOverClass : '') + // highlight selected day
(unselectable ? ' ' + this._unselectableClass + ' ui-state-disabled': '') + // highlight unselectable days
(otherMonth && !showOtherMonths ? '' : ' ' + daySettings[1] + // highlight custom dates
(printDate.getTime() == currentDate.getTime() ? ' ' + this._currentClass : '') + // highlight selected day
(printDate.getTime() == today.getTime() ? ' ui-datepicker-today' : '')) + '"' + // highlight today (if different)
((!otherMonth || showOtherMonths) && daySettings[2] ? ' title="' + daySettings[2] + '"' : '') + // cell title
(unselectable ? '' : ' onclick="DP_jQuery_' + dpuuid + '.datepicker._selectDay(\'#' +
inst.id + '\',' + printDate.getMonth() + ',' + printDate.getFullYear() + ', this);return false;"') + '>' + // actions
(otherMonth && !showOtherMonths ? ' ' : // display for other months
(unselectable ? '<span class="ui-state-default">' + printDate.getDate() + '</span>' : '<a class="ui-state-default' +
(printDate.getTime() == today.getTime() ? ' ui-state-highlight' : '') +
(printDate.getTime() == selectedDate.getTime() ? ' ui-state-active' : '') + // highlight selected day
(otherMonth ? ' ui-priority-secondary' : '') + // distinguish dates from other months
'" href="#">' + printDate.getDate() + '</a>')) + '</td>'; // display selectable date
printDate.setDate(printDate.getDate() + 1);
printDate = this._daylightSavingAdjust(printDate);
}
calender += tbody + '</tr>';
}
drawMonth++;
if (drawMonth > 11) {
drawMonth = 0;
drawYear++;
}
calender += '</tbody></table>' + (isMultiMonth ? '</div>' +
((numMonths[0] > 0 && col == numMonths[1]-1) ? '<div class="ui-datepicker-row-break"></div>' : '') : '');
group += calender;
}
html += group;
}
html += buttonPanel + ($.browser.msie && parseInt($.browser.version,10) < 7 && !inst.inline ?
'<iframe src="javascript:false;" class="ui-datepicker-cover" frameborder="0"></iframe>' : '');
inst._keyEvent = false;
return html;
}
}
);