window.onload = function () {
        var spread1 = document.getElementById("<%=FpSpread1.ClientID %>");
        if (document.all) {
            // IE
            if (spread1.addEventListener) {
                // IE9
                spread1.addEventListener("LoadRowsStart", loadStart, false);
                spread1.addEventListener("LoadRowsStopped", loadStop, false);
            } else {
                // Other versions of IE and IE9 quirks mode (no doctype set)
                spread1.onLoadRowsStart = loadStart;
                spread1.onLoadRowsStopped = loadStop;
            }
        } else {
            // Firefox
            spread1.addEventListener("LoadRowsStart", loadStart, false);
            spread1.addEventListener("LoadRowsStopped", loadStop, false);
        }
    }  
   
    function loadStart(event) {
      alert("start");
  }

  function loadStop(event) {
      alert("stopped");
  }