You might want to open two files in two separate windows to compare them. Also, if you want to edit two files simultaneously, you need to open them separately. That is why you can change Notepad ...

Source: Charlotte Cuthbertson/ Attribution-NonCommercial (CC BY-NC 2.0) This post was co-written by my colleague Cindy Harmon-Jones, who is first author on the manuscript reporting these results.