How to show the CalendarExtender over a dropdown?

1. Add a new item (Style Sheet) to your project and call it ajaxcalendarfix.css
2. In the css file paste the following:
.ajax__calendar
{
position: relative;
left: 0px !important;
top: 0px !important;
visibility: visible;
display: block;
}
.ajax__calendar iframe
{
left: 0px !important;
top: 0px !important;
}

3. In your MasterPage (or aspx page if you're not using a MasterPage) include the following line in your "head" section below all other css entries (change the path for your unique setup):



4. In the CssClass properties of your Calendar Extender, type: ajax__calendar ajaxcalendarfix
Note the space character between "ajax__calendar" and "ajaxcalendarfix".
This will take the default css properties of the Ajax Calendar and apply the bug fix in ajaxcalendarfix. Using this solution, I didn't have to mess with div tags, IFrames, z-indexes, etc.