no minimize/maximize buttons

edit

KDE/Plasma on Fedora 25 was working okay until today. I accepted an update, continued to work okay, then the desktop crashed (this seems to be an issue with the latest desktop). The system locked up when I tried to log back in and needed to be shut down to get back to the desktop.

Now... Application windows don't have minimize, maximize, or quit buttons. Application windows cannot be relocated (dragged) to a different position on the screen AND if I open a second application, I can't change between the applications. (Alt-F4 won't close the window, Alt-tab won't toggle between windows.)

Any idea what happened????