feat: finally.

src/Ursa/Controls/DateTimePicker/CalendarContext.cs

@@ -0,0 +1,16 @@
+namespace Ursa.Controls;
+
+public class CalendarContext(int? year = null, int? month = null, int? day = null)
+{
+    public int? Year = year;
+    public int? Month = month;
+    public int? Day = day;
+    public int? StartYear;
+    public int? EndYear;
+
+
+    public CalendarContext Clone()
+    {
+        return new CalendarContext(Year, Month, Day) { StartYear = StartYear, EndYear = EndYear };
+    }
+}