This example demonstrates the 
ASP.NET AJAX Calendar range selection between dates. To enable range selection     feature you need to set the 
RangeSelectionMode property to one of the following     values:
- OnKeyHold - Allow range selection by pressing [Shift] key and clicking             on the date.
- ConsecutiveClicks - Allow range selection by clicking consecutively two dates.
     By default the 
RangeSelectionMode property is set to 
None which does     not allow range selection.     
     The range selection Start/End dates are available:     
- On client through RadCalendar.get_rangeSelectionStartDate() and RadCalendar.get_rangeSelectionEndDate()             functions
- On server through RadCalendar.RangeSelectionStartDate and RadCalendar.RangeSelectionEndDate             properties
     You could set dates in range programmatically by using:     
- RadCalendar.RangeSelectionStartDate and RadCalendar.RangeSelectionEndDate             properties server side
- RadCalendar.set_datesInRange(startDate, endDate) function client side
Please note that when the dates in range are selected any other date selection will         unselect all dates from range selection