ui/src/main/java/ucar/util/prefs/ui/PrefPanel.java
public Field.Date addDateField(String fldName, String label, Date defValue) {
    Field.Date fld = new Field.Date(fldName, label, defValue, storeData);
    addField( new FieldResizable(fld, this));
    return fld;
  }
public Field.Date addDateField(String fldName, String label, Date defValue) {
    Field.Date fld = new Field.Date(fldName, label, defValue, storeData);
    addField( new FieldResizable(fld, this));
    return fld;
  }
Add a field that edits a date
@param fldName the name to store the data in the PersistenceManagerData
@param label used as the label on the panel
@param defValue default value