Here's what I did:
The system is now well and truly locked up; the best way out seems to be a reboot.

System is:
Operating System: Fedora Linux 36
KDE Plasma Version: 5.24.5
KDE Frameworks Version: 5.93.0
Qt Version: 5.15.3
Kernel Version: 5.17.13-300.fc36.x86_64 (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-4790K CPU @ 4.00GHz
Memory: 15.4 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 4600

-- 
Sincerely Jonathan Ryshpan <jonrysh@pacbell.net>

	For I am a Bear of Very Little Brain, and 
	long words bother me. -- Winnie the Pooh