Added Block Focus Option

[rachitkataria13]

Was useful for me to block in a certain webpage which used to add anomaly to the page when triggering focus without blur first and its completely optional to enable if but I may have left it enabled by default. change that if you wish and sorry, Its not such a big feature.

To check you can use the following JavaScript on any website with jQuery.

var i = 0;
$(window).focus(function() {
    i++;
    console.log(i);
});
$(window).blur(function() {
    console.log("Tabbed Out");
});