This custom System.EventArgs class provides additional information for the Calendar.VisibleMonthChanged event. The additional information consists of two properties: PreviousDate and NewDate (which will typically be the first of the newly selected month).
public sealed class MonthChangedEventArgs { // Public Constructors public MonthChangedEventArgs(DateTime newDate, DateTime previousDate); // Public Instance Properties public DateTime NewDate{get; } public DateTime PreviousDate{get; } }