function initMap() {

  var map = new GMap2(document.getElementById("container_frb"));
  map.addControl(new GLargeMapControl());
  map.setCenter(new GLatLng(52.43,-3.80), 7);

  var request = GXmlHttp.create();
  request.open("GET", "gen-gigfap.php", true);
  request.onreadystatechange = function() {
    if (request.readyState == 4) {
      var xmlDoc = request.responseXML;
      var markers = xmlDoc.documentElement.getElementsByTagName("marker");
      for (var i = 0; i < markers.length; i++) {
        var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),
                               parseFloat(markers[i].getAttribute("lng")));

        var minipages = xmlDoc.documentElement.getElementsByTagName("minipage");
        var infoPane = GXml.value(minipages[i]);

        var marker = createMarker(point,infoPane);
        map.addOverlay(marker);
      }
    }
  }
  request.send(null);

}

function createMarker(point,html) {
  var marker = new GMarker(point);
  GEvent.addListener(marker, "click", function() {
    marker.openInfoWindowHtml(html);
  });
  return marker;
}