function prepareCalendarPopup(input_id, button_id) {
  var calendar_input_id = input_id;
  var calendar_button_id = button_id;
  YAHOO.util.Event.onDOMReady(function(){
    var Event = YAHOO.util.Event,
    Dom = YAHOO.util.Dom,
    dialog,
    calendar;
    var showBtn = Dom.get(calendar_button_id);

    Event.on(showBtn, "click", function() {
      // Lazy Dialog Creation - Wait to create the Dialog, and setup document click listeners, until the first time the button is clicked.
      if (!dialog) {
        // Hide Calendar if we click anywhere in the document other than the calendar
        Event.on(document, "click", function(e) {
          var el = Event.getTarget(e);
          var dialogEl = dialog.element;
          if (el != dialogEl && !Dom.isAncestor(dialogEl, el) && el != showBtn && !Dom.isAncestor(showBtn, el)) {
            dialog.hide();
          }
        });

        function resetHandler() {
          // Reset the current calendar page to the select date, or
          // to today if nothing is selected.
          var selDates = calendar.getSelectedDates();
          var resetDate;

          if (selDates.length > 0) {
            resetDate = selDates[0];
          } else {
            resetDate = calendar.today;
          }

          Dom.get(calendar_input_id).value = "";

          calendar.cfg.setProperty("pagedate", resetDate);
          calendar.render();
        }

        function closeHandler() {
          dialog.hide();
        }

        dialog = new YAHOO.widget.Dialog("container", {
          visible:false,
          context:[calendar_button_id, "tl", "bl"],
          buttons:[ {
            text:"Clear",
            handler: resetHandler,
            isDefault:true
          }, {
            text:"Close",
            handler: closeHandler
          }],
          draggable:false,
          close:true,
          width:'210px',
          height:'280px'
        });
        dialog.setHeader('Choose the date');
        dialog.setBody('<div id="cal"></div>');
        dialog.render(document.body);

        dialog.showEvent.subscribe(function() {
          if (YAHOO.env.ua.ie) {
            // Since we're hiding the table using yui-overlay-hidden, we
            // want to let the dialog know that the content size has changed, when
            // shown
            dialog.fireEvent("changeContent");
          }
        });
      }

      // Lazy Calendar Creation - Wait to create the Calendar until the first time the button is clicked.
      if (!calendar) {
        calendar = new YAHOO.widget.Calendar("cal", {
          iframe:false,          // Turn iframe off, since container has iframe support.
          hide_blank_weeks:true, // Enable, to demonstrate how we handle changing height, using changeContent
          navigator:true
        });

        calendar.cfg.setProperty("MY_LABEL_MONTH_POSITION", 1);
        calendar.cfg.setProperty("DATE_FIELD_DELIMITER", "-");

        calendar.cfg.setProperty("MDY_DAY_POSITION", 3);
        calendar.cfg.setProperty("MDY_MONTH_POSITION", 1);
        calendar.cfg.setProperty("MDY_YEAR_POSITION", 2);
        calendar.cfg.setProperty("START_WEEKDAY", true);

        calendar.render();

        calendar.selectEvent.subscribe(function() {
          if (calendar.getSelectedDates().length > 0) {
            var selDate = calendar.getSelectedDates()[0];
            var dStr = selDate.getDate();
            var mStr = selDate.getMonth()+1;
            var yStr = selDate.getFullYear();

            Dom.get(calendar_input_id).value = yStr + "-" + mStr + "-" + dStr;
          } else {
            Dom.get(calendar_input_id).value = "";
          }
          dialog.hide();
        });

        calendar.renderEvent.subscribe(function() {
          // Tell Dialog it's contents have changed, which allows
          // container to redraw the underlay (for IE6/Safari2)
          dialog.fireEvent("changeContent");
        });
      }

      var seldate = calendar.getSelectedDates();
      if (seldate.length > 0) {
        // Set the pagedate to show the selected date if it exists
        calendar.cfg.setProperty("pagedate", seldate[0]);
        calendar.render();
      }
      dialog.show();
    });
  });
}