if(navigator.appName == 'Netscape'){ 

windowwidth = window.innerWidth;
windowheight = window.innerHeight;

}else if(navigator.appName == 'Microsoft Internet Explorer'){ 

windowwidth = document.documentElement.clientWidth;
windowheight = document.documentElement.clientHeight;
}

document.open();
document.write('<div style=\"width:0px;height:'+windowheight+'px\"><img src=\"spacer.gif\" width=\"1px\" height=\"'+windowheight+'\"></div>');
document.close();