the rare mouse focus issue

[deeptech71 at gmail.com]

OK, without a doubt, I have determined that my case is related to
"faulty" hardware. It seems that a half a year ago, when I was
throwing my (USB) mouse around my house, the mouse deformed into a
shape in which some (special) mouse button was stuck and was pressed
down continuously. That was the cause of the focus issue. A few days
ago the issue disappeared, when the mouse got re-deformed so that the
previously mentioned button was not stuck anymore.

That button, IIRC, has some "universal forward" meaning. I remember
using it for traversing through the browser history long, long ago,
for testing, but otherwise I've never used it.

Surprizingly, I noticed some notably similar focus misbehaviour in
Windows XP, but that disappears when I open a task manager and click
on a task (until a reboot), so I didn't notice it. Other mice do not
cause misbehaviour in either OS.

This explains everything, and means Xorg doesn't need to be "fixed".
But as some others have reported, the actual hardware behind it may be
a KVM switch or something else, so it's beyond the control of some
users. So I ask for a workaround (patch?) to disable/block specific
mouse buttons, or for someone to point us in the right direction if
there is already an option for that (I only tried things with
xorg.conf's option "ZAxisMapping").