Thanks to all for the suggestions. My hunch is that it is the window manager. My setup is very similar to Woodsman's except that I use xfce instead of KDE. Here is what I'm going to try.
1. Switch window manager to KDE. Test.
2. If that fails, install from the package suggested by Woodsman.
If that still fails, I'll look around some more and see what comes up. I'm in no hurry.
And oh! thanks to eternal_newbie for the concern. I'll be careful. I extracted the tarball into /usr/lib because I don't care if I screw up. I'll just re-install everything. Besides, I've used Unix for some time now (about 20 years) and think I know my way around. I started with SVR4, then Olivetti's Unix (I forgot the name, it was so long ago, XOS I think it was called. It was a huge proprietary box, 32-bit thingy with 5 inch floppy), Solaris, Microsoft Xenix (yes, it's true they have a *nix too), SCO Unix 386, SCO Xenix 386, HP-UX 9, then 10. And finally Linux; started with Slackware on kernel 1.1.59, Slack 7, 10 and now 12.2.