First of all, I apologize if this is another case of user-is-half-asleep, aka an idiot. (I've already made one post of that kind, and then was unable to figure out how to delete it, or at least report it solved.)
Second of all, I'm aware that the following is useless as a bug report. Instead of gathering farther data, I rebooted the system, just as if it was a Windows box. All I'm looking for is whether people recognize the pattern and can point me to possible causes or work-arounds.
As of this morning when I woke up, my Kubuntu 25.10 system had been up for 7 days. It appeared to be mostly working, but when I selected the ProtonMail app, it looked funny, as if it wasn't being given focus, and didn't show recent email messages, which I could see from another device. I was able to switch to Firefox and Konsole Windows, which worked normally. So far, this looked like a ProtonMail issue. But then I tried to select the Discord app, and got essentially the same behaviour - missing recent messages. I'm not sure whether it also had the doesn't-look-selected glitch.
Multiple attempts to select either of these apps and get them to refresh failed. I spent some time killing off firefox windows, so they wouldn't respawn after a restart. In doing this I verified I could switch virtual desktops, using the tool in the panel. I could select app windows, provided they weren't Discord or ProtonMail. I could run shell commands in Konsole windows.
The two apps are unrelated. All they have in common are that they don't come from Ubuntu repos, and part of their job is to receive and display things that are happening on a server somewhere in the cloud.
I therefore figure the problem probably isn't with them, but somehow with Kubuntu. It smells to me like a Desktop environment bug, mostly because the alternative would seem to be the kernel scheduler, or the networking stack.
I don't recall whether I did anything before rebooting that would have told me for sure that the kubuntu system was successfully communicating with the internet. Other systems on the same LAN were talking happily to the net, e.g. successfully running ProtonMail and Discord, and internet connectivity was fine after I rebooted.
Discord version 0.0.126 at the time; after the reboot, I was forced to upgrade it to 0.0.127
ProtonMail version unknown; it doesn't seem to want to tell me, but it too is pushy about insisting that everyone upgrade as soon as a new version comes out.
p.s. ProtonMail had been set to show on all virtual desktops, and Discord might have been. They are essentially the only apps I ever set that way.
p.p.s. I tried to select them by clicking on them/their title bars, not by clicking on their icon in the task manager.
p.p.p.s. If it happens again, I'll try to gather some more useful data, rather than rebooting to clear the problem.
Second of all, I'm aware that the following is useless as a bug report. Instead of gathering farther data, I rebooted the system, just as if it was a Windows box. All I'm looking for is whether people recognize the pattern and can point me to possible causes or work-arounds.
As of this morning when I woke up, my Kubuntu 25.10 system had been up for 7 days. It appeared to be mostly working, but when I selected the ProtonMail app, it looked funny, as if it wasn't being given focus, and didn't show recent email messages, which I could see from another device. I was able to switch to Firefox and Konsole Windows, which worked normally. So far, this looked like a ProtonMail issue. But then I tried to select the Discord app, and got essentially the same behaviour - missing recent messages. I'm not sure whether it also had the doesn't-look-selected glitch.
Multiple attempts to select either of these apps and get them to refresh failed. I spent some time killing off firefox windows, so they wouldn't respawn after a restart. In doing this I verified I could switch virtual desktops, using the tool in the panel. I could select app windows, provided they weren't Discord or ProtonMail. I could run shell commands in Konsole windows.
The two apps are unrelated. All they have in common are that they don't come from Ubuntu repos, and part of their job is to receive and display things that are happening on a server somewhere in the cloud.
I therefore figure the problem probably isn't with them, but somehow with Kubuntu. It smells to me like a Desktop environment bug, mostly because the alternative would seem to be the kernel scheduler, or the networking stack.
I don't recall whether I did anything before rebooting that would have told me for sure that the kubuntu system was successfully communicating with the internet. Other systems on the same LAN were talking happily to the net, e.g. successfully running ProtonMail and Discord, and internet connectivity was fine after I rebooted.
Discord version 0.0.126 at the time; after the reboot, I was forced to upgrade it to 0.0.127
ProtonMail version unknown; it doesn't seem to want to tell me, but it too is pushy about insisting that everyone upgrade as soon as a new version comes out.
p.s. ProtonMail had been set to show on all virtual desktops, and Discord might have been. They are essentially the only apps I ever set that way.
p.p.s. I tried to select them by clicking on them/their title bars, not by clicking on their icon in the task manager.
p.p.p.s. If it happens again, I'll try to gather some more useful data, rather than rebooting to clear the problem.