function dester1(e) { 
if (navigator.appName == 'Netscape' && (e.which > 1)){ 
return false; 
} 
{ 
return true; 
} 
} 
function dester2(){ 
return false; 
} 
document.onmousedown=dester1; 
document.onmouseup=dester1; 
document.oncontextmenu = dester2;