function showExtent(extent) {
   
    //show extent in div
    var s = "";
    s = "<b>Map Extent:</b><br/>XMin: " + extent.xmin + "&nbsp;"
           + "YMin: " + extent.ymin + "&nbsp;"
           + " XMax: " + extent.xmax + "&nbsp;"
           + "YMax: " + extent.ymax;
    dojo.byId("extent").innerHTML = s;
}