Gets a value that indicates whether this button represents a day that is not in the currently displayed month.
Assembly: PresentationFramework (in PresentationFramework.dll)
When the DisplayMode of a calendar is Month, it might display days that are not in that month. For example, a calendar that shows March 2009 also displays the days February 22 through February 28 and April 1 through April 4. Because those dates are not in the month of March, the IsInactive property is set to true for the buttons that represent those days.
Available since 4.0