xfce4 panel items don't react but show their functions on mouse over

[Adalbert Hanßen]

This is the second time that I encounter this bug in Xubuntu 16.04.3 LTS with current kernel 4.4.0-116-generic x86_64.

Two applications were running: Firefox and LibreOffice 6.1. I could not start any other application using the xfce4-panel, not even the whisker menu. However, after pointing with the mouse to one the buttons on the panel, after a short while its explanation was shown to me.

Switching between the running programs the Alt-Tab-way worked.

Since I could neither switch to another screen nor to the other running application nor shut down orderly via the panel way, I opened a terminal by a right click on the desktop and started a terminal there.

In this terminal I issued the command xfce4-terminaal --restart.

Then the buttons on the xfce4-panel worked again. I could switch between the running applications and between different desktops. However the system reacted strange: When I shifted windows on my screen, they left a trace.

I terminated the two running applications by their own terminate buttons.

I suspected that the system was in some strange state and therefore I issued shutdown -r to get out orderly.

[Theo Linkspfeifer (lastonestanding)]

I suggest that you monitor the overall CPU and RAM usage.

[Adalbert Hanßen (melolontha)]

I have these meters showing the cpu, memory and swap usage in the xfce panel. They did not show suspicious activities. I did not take a notice on that, but if anything goes wrong I look at these indicators and if the blue CPU usage bar would have been completely up or the green Memory bar or if anything would show on the yellow Swap bar, I definitely would have seen that and taken a note on it.

It was an error which I encountered just two times. Far from a reproducible bug!

If I happen to encounter it again: What kind of information to note to some file? What kind of commands to run in a terminal then to squeeze out the right information? (Btw: This might be a general advice what to supply to you experts if something really strange like this happens).

My first concern was how to orderly stop the computer without using the xfce4-panel and I was happy that I finally could open a terminal by a right-click on the desktop.

[Theo Linkspfeifer (lastonestanding)]

Xfce session related errors are logged in ~/.xsession-errors (.old for the previous session).

Also, it is worth to check system messages with "dmesg" or "journalctl". Memory usage can be displayed with "free -m".

[Adalbert Hanßen (melolontha)]

Today this happened again (I don't know why).

~/.xsession-errors told me (with a timestamp some hours ago, when the system still worked properly):

openConnection: connect: Datei oder Verzeichnis nicht gefunden
cannot connect to brltty at :0

However, after I shut down the whole system and rebooted, it told exactly the same, but the file had a timestamp close to the reboot.

dmesg showed, that I connected and disconnected the LAN cable seveal times (ok, I did it) and that I connected an usb device and then it showed that the computer connected to WLAN (wlp3s0: associated).

free -m shows me:

              gesamt benutzt frei gemns. Puffer/Cache verfügbar
Speicher: 7555 1197 311 214 6047 5810
Auslagerungsspeicher: 20479 2 20477

journalctl
Hint: You are currently not seeing messages from other users and the system.
      Users in the 'systemd-journal' group can see all messages. Pass -q to
      turn off this notice.
No journal files were opened due to insufficient permissions.

[Adalbert Hanßen (melolontha)]

I just saw this bug in the incomplete state. Which additional information is missing?

[Theo Linkspfeifer (lastonestanding)]

Sorry for the late reply. Before we try to look further into this, are you planning to upgrade to 18.04 LTS soon (Xubuntu LTS releases are supported for 3 years)?

[Launchpad Janitor (janitor)]

[Expired for xfce4 (Ubuntu) because there has been no activity for 60 days.]