UPDATE: The fixed version of mutter is now in the Fedora updates repository. You should be able to update the package with
dnf -y upgrade mutter
GNOME 3 has been rock solid for the last few months but something cropped up this week that derailed me for a short while. Whenever I moved my mouse cursor to the top bar (where the clock and status icons reside), the mouse cursor disappeared. The same thing happened if I pressed the Mod/Windows key to hop into the Activities display.
If I wiggled the mouse a bit, I could see the highlight move around to different windows and icons. The mouse cursor never appeared.
Lots of Google results led to dead ends. I stumbled onto a GNOME bug for gnome-shell from early 2015 that seemed to cover the same problem. After adding in my comments, I created a Fedora bug to track the problem.
Around that time, Florian Müllner replied in the GNOME bug about trying
mutter-3.18.3-2. My laptop was running
mutter-3.18.3-1 at the time. The new version of mutter was still in the pending state in Fedora’s packaging infrastructure, so I pulled it down with
koji download-build --arch x86_64 mutter-3.18.3-2.fc23 sudo dnf install mutter-3.18.3-2.fc23.x86_64.rpm
After a reboot, everything was back to normal! The cursor appears reliably in the top bar, Activities screen, and other overlays. In addition, some of the transient cursor weirdness I had with some applications seems to be gone.
UPDATE: Jiří Eischmann tweeted yesterday about this problem:
In my particular case, my “left” monitor is my laptop screen and my “right” monitor is my external display. I configure the external monitor to be above my laptop monitor physically and logically, which is why the problem appears for me. Thanks for the clarification, Jiří!