function openPopup(selector) {
  var element = $(selector+":hidden");
  
	if(element != undefined){
    // Hide select elements in IE 6
		if ($.browser.msie && $.browser.version == '6.0') {
      $("select").each(function() {
        $(this).hide();
      });
  	}
		element.fadeIn("slow");
  }
}

function closePopup(selector) {
  var element = $(selector+":visible");

	if(element != undefined) {
		element.fadeOut("slow");
		// Unhide select elements in IE 6
		if ($.browser.msie && $.browser.version == '6.0') {
      $("select").each(function() {
        $(this).show();
      });
  	}
  }
}

function centrePopup(selector) {
  var element = $(selector);

  var windowWidth = $(window).width();
  var windowTop = $(window).scrollTop();
  var popupWidth = element.width();
  var popupHeight = element.height();

  element.css({
	"position" : "absolute",
	"top"      : windowTop + (popupHeight/2),
	"left"     : (windowWidth/2) - (popupWidth/2)
  });
}

function openAjaxPopup(url, containerSelector, popupSelector) {
  $(containerSelector).load(url, function () {
    openPopup(popupSelector);
  });
}