Selecting already selected date in Calendar control

Greetings,

 I have a calendar control inside an UpdatePanel.

As indicated in the documentation (and verified by testing), the SelectionChanged event is triggered only if the selected date is changed. That is, it does not trigger if the user clicks on the already selected date.

 However, clicking on the already selected date does cause an async postback of the UpdatePanel that contains the calendar.

 So, my question -- how can I determine that the cause of the postback was the user clicking a second time on the calendar control? There does not appear to be a calendar event that covers clicking on the selected date.

 Thanks,

 Andrew
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