Not much of a mistake, because my plans were already that as soon as I get some free time I'll blow Mint away, replacing it with Lubuntu/Mate.
I downloaded an MP3 tonight. Not an unusual event. I right-clicked the MP3 with the intention of looking at the audio properties, which were nowhere to be seen. So, it turned out my system was all-of-a-sudden using Thunar. WTF? I know I had XFCE installed, but why was was Thunar suddenly the default?
I uninstalled Thunar, and tried again. Again, no audio properties. What's this? Nemo? WTF?
So I uninstalled Nemo. The next time I clicked on Places, I got Caja, which should be okay. But still no audio properties!
WTF Mate project? This is Caja 1.4.0, presumably newer and better than what I had been running, but clearly not better.
The same sorts of mistakes, over and over and over. When did update become the opposite of upgrade? After NT4? After SunOS 4? When did the Linux crowd decided to match Windows feature-for-feature and became as Windows-like as possible?