I have tried setting the MaskInput to yyyy (four-digit year) in the UltraDateTimeEditor, but it does not seem to work. It does work to set the MaskInput to mm/yyyy, but I want our users just to see/edit the year. The control correctly displays 2008 for the year, but when I click on it to edit the value it just displays yyyy!
I don't think this is supported. You can't have just a year without any other information about the date. If you are only storing a year, why use a DateTimeEditor? Why not just use an UltraNumericEditor with a mask of "nnnn"?
Since a MaskInput of mm/yyyy works in the UltraDateTimeEditor, I guess I thought that yyyy would also work. We were trying to use yyyy to represent Jan 1 of the year entered by the user. I will probably use the UltraNumericEditor instead, that's the workaround we had come up with as well.