When defining someone's birthday or anniversary it'd be good if the year
was optional as often you know the day and month but not the year.  Also
when you do know the year there's no quick way to use the mouse to enter
one that's quite a while back as the menu only shows 5 years at a time.

To achieve both of these the year could be separated from the day and month
and made into a drop down option box with an "unknown" (or blank) option
and lots of years (last 100?) in a scrollable list.  Also perhaps the
day/month picker shouldn't show years (and therefore days) in this case.