Drive was full, so I cleaned it up and provided more room. As a result, lost this version of Mate and the version I'm using now, doesn't have the problem so I'm good.
I don't really know how to describe this issue. It just popped up a while ago and I don't recall what might have triggered it. Just seemed to happen.
I'm perplexed. When I open a browser, that looks fine, so I did a search stumbling on what exactly to call the problem. I found a thread that might be it and I think reinstalled Mate's desktop using a crippled Term because it's affected too. I'm used to how it behaves so I could work with it. But after reboot the software install didn't seem to cure anything.
I seem to remember this from a few years ago but can't remember the fix.