function onLoginButton()
{
   frm = document.forms.frmLogin;
   // check form user name and password
   var strErrors = '';
   if (!frm.txtUser.value)
      strErrors += ' - Enter User Name\n';
   if (!frm.txtUserPass.value)
      strErrors += ' - Enter Password\n';

   // add error header and show error
   if (strErrors)
   {
     strErrors = 'Errors in submission:\n' + strErrors;
     alert(strErrors);
     return false;
   }

   // do submit
   return true;
}