XUL:Attribute:datepicker.type

type: Type: one of the values below; You can set the type attribute to one of the values below to specify the type of datepicker to use

normal: A datepicker with three fields for entering the year, month and date. This is the default value so do not specify the type attribute if this kind is desired.
grid: A datepicker that displays a calendar grid where one month is shown at a time.
popup: A datepicker with three entry fields but an additional dropdown button, which, when pressed, will display a popup calendar grid.