DateTimePicker: if the Calendar is open and has focus the Up/Down keys would not navigate the calendar as expected. This has been fixed.

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/DateTimePicker/Implementation/DateTimePicker.cs

@@ -98,6 +98,13 @@ namespace Microsoft.Windows.Controls
             base.OnValueChanged(oldValue, newValue);
         }
 
+        protected override void OnPreviewKeyDown(KeyEventArgs e)
+        {
+            //if the calendar is open then we don't want to modify the behavior of navigating the calendar control with the Up/Down keys.
+            if (!IsOpen)
+                base.OnPreviewKeyDown(e);
+        }
+
         #endregion //Base Class Overrides
 
         #region Event Handlers