When you have a load of tabs open, e.g. 10 tabs (or 100 tabs like many of my colleagues), often one tab can be accidentally dragged out of the main window, or a website/login authentication page opens a popup/popover dialog window; this second window is occasionally open when you click on the Close button to exit the browser. All of your open tabs (that you want to keep) disappear and the single window (which you don’t actually want) is left behind. I see this every week with someone in our office, and I don’t have any answer so far – surely there’s a way to prevent the browser from opening a second window like this ??