function winSize() {
  var myWidth = 0, myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  return {w:myWidth, h:myHeight};
}

function hideDiv(perform_at_div_id) {
  if (document.getElementById) {            // DOM3 = IE5, NS6
    document.getElementById(perform_at_div_id).style.visibility = 'hidden';
  }
  else {
    if (document.layers) {                  // Netscape 4
      document.perform_at_div_id.visibility = 'hidden';
    }
    else {                                  // IE 4
      document.all.perform_at_div_id.style.visibility = 'hidden';
    }
  }
}

function showDiv(perform_at_div_id) {
  if (document.getElementById) {            // DOM3 = IE5, NS6
    document.getElementById(perform_at_div_id).style.visibility = 'visible';
  }
  else {
    if (document.layers) {                  // Netscape 4
      document.perform_at_div_id.visibility = 'visible';
    }
    else {                                  // IE 4
      document.all.perform_at_div_id.style.visibility = 'visible';
    }
  }
}