The demo uses the following code:
TimeRangeSelectedHandling="JavaScript"
TimeRangeSelectedJavaScript="alert(start.toStringSortable() + '-' + end.toStringSortable())"
TimeRangeDoubleClickHandling="CallBack"
OnTimeRangeDoubleClick="DayPilotCalendar1_TimeRangeDoubleClick"
If I switch it to your example it works as well:
TimeRangeDoubleClickHandling="JavaScript"
TimeRangeDoubleClickJavaScript="alert('TimeRangeDoubleClick')"
Very strange, because it was indeed not working 7.3.2861 but since 2866 DayPilot includes a lot of new code to make it working reliably.
Can you please check that it is indeed using 7.3.2871 by checking the page HTML output? It should include a line like this:
/* DayPilotPro: DayPilot, Version=7.3.2871.0, Culture=neutral, PublicKeyToken=426941954f05e7fe */
Sometimes the old version gets cached somewhere....