document.oncontextmenu = function () { return false } 
// IE Evitar seleccion de texto
document.onselectstart=function(){
if (event.srcElement.type != "text" && event.srcElement.type != "textarea" && event.srcElement.type != "password")
return false
else return true;
};
// FIREFOX Evitar seleccion de texto
if (window.sidebar){
document.onmousedown=function(e){
var obj=e.target;
if (obj.tagName.toUpperCase() == "INPUT" || obj.tagName.toUpperCase() == "TEXTAREA" || obj.tagName.toUpperCase() == "PASSWORD")
return true;
/*else if (obj.tagName=="BUTTON"){
return true;
}*/
else
return false;
}
}