If you are facing an issue of jQuery ui calendar not appearing while clicked from a jQuery thickbox or if some part of the calendar hiding behind the thickbox window you need to apply a quick fix to your calendar.
Web & Mobile App Tech Weblog
If you are facing an issue of jQuery ui calendar not appearing while clicked from a jQuery thickbox or if some part of the calendar hiding behind the thickbox window you need to apply a quick fix to your calendar.