The Two Body Problem

A few days ago, a very strange GUI problem suddenly materialized that made me start sweating: After working on the notebook for a while, I suddenly could not switch between windows anymore and generally, the desktop started to behave very strangely. Suspend and resume helped, but after 15 to 20 minutes the desktop started to behave very strangely again. The same after a reboot. And, of course, this started happening just after making an update. So did the update actually cause it? I couldn’t see how, as nothing GUI related had changed. So I started to investigate and it took me several hours and several reboots to figure out what the problem was. And then I felt stupid.

This issue really had me on the edge, because a non-working desktop is kind of the worst case scenario. So I tried many things, checked the system log carefully for any strange error messages appearing once the mouse pointer and the windows started to behave strangely, but I came up with nothing. I even booted with the previous kernel but even here, things worked for a few minutes before the windows and mouse pointer started to act strangely again.

But finally, I noticed, due to sheer luck, that things started to go wrong at exactly the moment when I touched my backpack that was lying on the floor next to me. And it immediately hit me: The other mouse in the backpack must be switched on. And indeed this caused the problem! Whenever the backpack got moved, the mouse inside woke up from sleep mode and started sending mouse down events because the mouse button was pressed by something in the backpack. After switching the second mouse off, the problems disappeared immediately. I felt relieved and stupid at the same time…

So how could two mice actually connect at the same time? Well, both are Bluetooth mice, so I don’t have a USB dongle anymore that would limit me to a single mouse at a time. Ah well… A two mouse problem… That kind of reminds me of the chaotic movements of the three body problem

3 thoughts on “The Two Body Problem”

  1. It comforts me to know that experts can fall into the trap of catastrophizing. Thanks for sharing, there is a universal lesson in the story, chaos will forever have a finger in the pie.

  2. So we know that two mice can both be active at once.

    Do you know if apps have the ability to distinguish between the two mice?

    I ask because I remember some games on the Commodore Amiga supporting two-mouse operation, allowing two players to point-and-click at different things at the same time (using different colored pointers).

    It would be kind of neat if some modern games (on any platform – Linux, Mac or Windows) would be capable of doing the same thing.

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