Hello Ingo,

In order to set the time of the XamDateTimeEditor to "00:00" when leaving edit mode, I can suggest you handle the EditModeEnding event of the XamDataGrid (presuming you are using the editor within a XamDataGrid) by accessing the editor's Text property and replacing the existing time separator ":" with "00:00" and concatenate the year part to the date section.

e.Editor.Text = e.Editor.Text.Replace(e.Editor.Text.Substring(0, e.Editor.Text.LastIndexOf("/")),
                                        e.Editor.Text.Substring(0, e.Editor.Text.LastIndexOf("/")) + (DateTime.Now.Year % 100).ToString());
e.Editor.Text = e.Editor.Text.Replace(":", "00" + ":" + "00");

Since by the time this event is fired the XamDateTimeEditor has not committed its value, we do not have access to a DateTime instance that contains the new value. This is why we will have to manually adjust the Text property according to the desired behavior.

I have attached a sample application that demonstrates the approach from above and you can use it as a starting point for implementing the functionality you are looking for.

If you have any questions, please let me know.