property Calendar.NonworkingDaysFrameColor as Color
Retrieves or sets a value that indicates the color to show the non-working frame.

TypeDescription
Color A Color expression that specifies the color to show the frame on non-working dates on the calendar panel. 
If the NonworkingDaysPattern property includes the exPatternFrame, the NonworkingDaysFrameColor property indicates the color to show the frame around nonworking days. The NonworkingDaysFrameColor property has no effect if the NonworkingDaysPattern property includes NO exPatternFrame flag. Use the NonworkingDays property to specify the nonworking days. Use the NonworkingDaysPattern property to specify the pattern to fill non-working days. If the NonworkingDaysPattern property is exPatternEmpty or NonworkingDays property is 0 the non-working days are not highlighted. The NonworkingDaysColor property specifies the color being used to fill the non-working days.