I've tried unplugging and replugging the mouse. It's doesn't help.
When this occurs, the Yast window has focus. I can't close it, nor can I
switch focus to the CLI terminal window. Also, Yast used to have a way
of looking at system messages which no longer exists. Rather hard to
find out anything when you can't get to it. It will let me log out,
without returning the mouse action, and shut down. Rebooting fixes the
problem, provides proper scanner access, but does not retain any of the
information that would.
I checked /var/log/messages after reboot and found all references to
CanoScan are on usb 3-1 and all references to mouse are on usb 4-1. If
they were on the same one, it's not recorded. Also, I suspect that the
numbers relate to the tree structure of the USB hardware setup, and that
has not changed.
John