I still use xv to look at images, GLXGears to debug GL issues, and xev to debug any weird keymapping issues, and xterm as a visually different terminal for things like monitoring console output.
It's such a quick and handy tool that I became habituated to xv over a decade of use. Some years ago though, I found it was no longer available to install after an upgrade. I was eventually able to fudge a working version from old code and patches and taking hints (iirc) from some patches for MacOS, but now that has suffered bitrot.
So I'm curious what OS you're running and where your xv is from? Still miss it!
