Short forms are only accepted in interactive mode (e.g. when using the
"Go to" function, editing a recurrent item's end date, and so on).
Samples: "1/1/30" for "01/01/2030", "26" for the 26th of the currently
selected month/year or "3/1" for Mar 01 (or Jan 03, depending on the
date format) of the currently selected year.
