function showSelectMenus(target){
		var opts = $.data(target, 'calendar').options;
		$(target).find('.calendar-menu').show();
		
		if ($(target).find('.calendar-menu-month-inner').is(':empty')){
			$(target).find('.calendar-menu-month-inner').empty();
			var t = $('<table class="calendar-mtable"></table>').appendTo($(target).find('.calendar-menu-month-inner'));
			var idx = 0;
			for(var i=0; i<3; i++){
				var tr = $('<tr></tr>').appendTo(t);
				for(var j=0; j<4; j++){
					$('<td class="calendar-nav calendar-menu-month"></td>').html(opts.months[idx++]).attr('abbr',idx).appendTo(tr);
				}
			}
		}
		
		var body = $(target).find('.calendar-body');
		var sele = $(target).find('.calendar-menu');
		var seleYear = sele.find('.calendar-menu-year-inner');
		var seleMonth = sele.find('.calendar-menu-month-inner');
		
		seleYear.find('input').val(opts.year).focus();
		seleMonth.find('td.calendar-selected').removeClass('calendar-selected');
		seleMonth.find('td:eq('+(opts.month-1)+')').addClass('calendar-selected');
		
		sele._outerWidth(body._outerWidth());
		sele._outerHeight(body._outerHeight());
		seleMonth._outerHeight(sele.height() - seleYear._outerHeight());
	}
show the select menu that can change year or month, if the menu is not be created then create it.