This one is about capturing the width of the viewport through Google Analytics. Basically GA will only track the device width. This is fine for tablet and phone because it’s rare (or is it even possible at all) to change the width of the browser other than full screen.
With laptops and monitors though you can change the width based on your particular setup. This tip will allow you to track the width of the browser, rather than just the device.
As marketers, we want to know which layouts and designs work, and which ones don’t. If you’ve ever wanted a way to track how users respond to content as it changes from one device to another, here it is:An excerpt from Tracking Events Responsively With The New Google Analytics