XYplorer Beta Club

You can make it wider by right clicking while having the horiz resize cursor over it, its color isn't adjustable other than by changing the whole main interface color, the easiest way to do that is via

Configuration | Colors and Styles | Highlights & Dark Mode | Dark mode

@jupe, thanks much. that's awesome. for anyone else wanting to see how to do it, here you go: https://i.imgur.com/CQkc4X9.mp4

edit: oh! and Configurations - Highlights and Dark Mode - Borders (set to windows classic style) put a small, but noticeable border around the active windows. Love it!