How can I block multiple Browser Windows from opening

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 :x: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 ??