I am not sure I fully understand your scenario as the RadDateTimePicker for WPF does not posses a SelectedDateChanged event. If you mean the SelectionChanged event we have tested it in both of the described scenarios - when selecting date by clicking on the date and when selecting date when inputting it in to the WatermarkTextBox
, but the SelectionChanged event is thrown as expected.
I am attaching my test application and a video showing how it behaves on my machine. It would be great if you can give it a try and let me know if I am not missing something.
Also can you confirm that you are using 2013.1.403 version of the controls ?
the Telerik team