A good solution is to force popup windows to open as a tab in the current window, so that the address bar is absolutely always in the same place. This distorts the popup window because it can't change size but that's a small price to pay. I find it annoying that any website should open a new window anyway. I'm not sure if this is possible in Chrome, or if so how to do it, but in Firefox the setting is browser.link.open_newwindow.restriction.
It would also help if Windows had proper contrast between the title bars of active and inactive windows, since then it would be obvious there's a problem from the two simultaneously active top-level windows. The contrast was excellent from at least Windows 3.1 through to Windows XP (colour vs greyscale) but in Windows 7 it dropped dramatically, and it's almost indistinguishable in Windows 10. Microsoft seems to have an endemic problem of redesigning visual styles for the sake of it, even if it makes things worse, presumably to justify the wages of full-time designer staff.
If you go to the page, you'll notice that they are not displaying a popup. Instead, they have recreated the entire UI experience, and if you're on Windows the only way to tell that something fishy is going on is if you try to move the window and you'll notice you can't move it outside the bounds of the parent Window.
It's incredibly well done, and I was almost fooled by it when I went to the web site. If I hadn't been using Qubes OS where my dispvm's are using red borders, I probably wouldn't have noticed at all.
But that's exactly my point! If you have set your browser to make all popups appear as a tab taking up the whole of your existing window (and adding an entry to your tab list), and then a fake one looks like a separate window, then it will stick out as fake immediately. For me, a browser-like window within the boundary of my actual browser is so foreign that I wouldn't even consider the possibility that it's real.
One of the benefits of being a long-time Linux desktop user who uses some non-standard window manager and a motley mix of Gnome, KDE, and "standard" X11 apps; good luck guessing from my browser string what a new window looks like.
Currently I'm on a tiling manager, and the "window decoration" is a three-pixel thick blue line, which even if you draw it in the middle of a web page is still wrong, because your supposed new window didn't tile correctly.
On those rare occasions where someone gets through the various NoScript-type protections I tend to run, it's amusing to see a Windows screen pop up. Yes, sir, I'll get right on running Windows Update on my Ubuntu system. (Do I have to install Wine for that, or...?) I've also seen some Windows-styled screens pop up on my Android browser on occasion... yeah... not terribly convincing there guys.
