The RadCalendar control raises server-side events, which you can use to customize the parts of the control as they are created, or to respond in the code-behind when the user makes a change.
RadCalendar exposes the following server-side events:
DayRender occurs immediately before the calendar renders the cell for a single day in the day matrix.
HeaderCellRender occurs immediately before the calendar renders a cell in the column or row headers (or the view selector).
SelectionChanged occurs when the user changes the current selection in the calendar. This event does not fire unless the AutoPostBack property is True.
DefaultViewChanged occurs when the user changes the current view using the navigation controls in the title bar. This event does not fire unless the AutoPostBack property is True.
By default, the RadCalendar does not cause postbacks when the user selects or deselects a date. This means that the server-side events are not raised. To enable postback to be triggered you should set the AutoPostBack property to true.