Fire event on window blur if page is visible

[DanielKucal]

If our page contains an iframe and user clicks on it - it is outside click, but web browser doesn't emit proper event due to security reasons. It would be great to have a work-around for it. I suggest to listen to window blur event and emit outside click event if page is visible like in the following example:

    window.addEventListener('blur', () => {
        setTimeout(() => {
            if (!document.hidden) {
                console.log('outside click event');
            }
        });
    });

Let me know what you think, so I will prepare PR.

[DanielKucal]

@arkon, could you have a look at this topic?

[arkon]

Sounds reasonable. An option called [emitOnBlur] or something would make sense.