Any ideas what this could be? Its happened a couple of times.
I will be doing something perfectly ordinary in Firefox, like shopping on Amazon was the last one. All of a sudden the mouse cursor, as I move the mouse, turns into a broad black stream, which makes a trail a half inch or so wide, quite jagged. Stays in place as the mouse is moved on. In and out of the browser window. Its impossible to close the window. More clicking brings up partial truncated small windows. Right clicks have no effect.
The only thing I could find to do to get out of it was reboot.
This is Debian 11, fluxbox, using the Nvidia drivers for their card. Never happened with any other app, including not with any other browser. Doesn't happen often, maybe three or four times over several months.
I shall be upgrading to Debian 12 fairly soon, so maybe that will make it go away. But what could it be? And what would you do, other than upgrading?
Peter