protected void Page_Load(object sender, EventArgs e)
{
  if (!this.Page.IsPostBack)
  {
   this.Page.Master.Page.Form.DefaultButton = this.BtnSave.UniqueID;

var __defaultFired = false;
function WebForm_FireDefaultButton(event, target) {
 if (!__defaultFired && event.keyCode == 13 && !(event.srcElement && (event.srcElement.tagName.toLowerCase() == "textarea"))) {
  var defaultButton;
  if (__nonMSDOMBrowser) {
   defaultButton = document.getElementById(target);
  }
  else {
   defaultButton = document.all[target];
  }
  if (defaultButton && typeof(defaultButton.click) != "undefined") {
   __defaultFired = true;
   defaultButton.click();
   event.cancelBubble = true;
   if (event.stopPropagation) event.stopPropagation();
   return false;
  }
 }
 return true;
}