CentOS

After recent software upgrade, something strange happened.
In my setting (I don't know how to make this gnome desktop environemt), the workspace index appears on bottom (Windows list) right corner as "1/3" style.
After recent upgrade, it does not work. When I click the icon (1/3 such thing), it does not give any response though it is activated when I put mouse point on it. Even more the workspace selector disappeared. When I go to "Activities" and move mouse to the rightmost side or any, there is no workspace selector exists or appears. How to recover the "workspace selector"?

Sometimes the selector appear on the left-top on terminal, but it does not response. Normally it should appear just on top of the "1/3" icon on the bottom left.

I can use ctrl + alt + up/down and switch workspace, but I can't move any window to an other workspace without workspace selector.

Would you help me this problem?

Joonho

In 7.8 they are horizontal now - click to the right of it. If you look closely, by the way, you can see (much dimmer) panes. I've no idea why; it's Gnome.

Also for many people the 7.8 update has reset their desktop from gnome to gnome-classic and you may need to reselect the non-classic gnome one at login to get it back.

I have checked the gnome and it is gnome and not gnome-classic.
But even gnome-classic shows workspace selector.
I have changed the some file and directories with some initial files saved in the start of centos installation.
Those are ~/.local/share/gnome-shell, gnome-settings-daemon gsettings-data-convert.

And reboot, something changed and I can see the workspace selector in Activities.
And now, another problem happens in Virtual Machine where VM can't open the file with error.
"Cannot attach medium '/usr/share/virtualbox/VBoxGuestAdditions.iso' {c60a1be4-3ff8-41fe-a6d0-d28bad5f73b4}: medium is already associated with the current state of machine uuid {e7830ebf-1af4-465c-aafc-905cf9410db8}!."
It looks very difficult to solve this problem though there are many sites related with this issue and those looks all are different cases.
Is there any solution for this?

And I might try another method after recovering the previous files.
What can I try? Uninstall gnome and reinstall would be effective?

I have changed the some file and directories with some initial files saved in the start of centos installation.
Those are ~/.local/share/gnome-shell, gnome-settings-daemon gsettings-data-convert.

If it were me, I'd start my troubleshooting there.

That's right.
I have fixed the virtualbox problem.
And now I start from the saved gnome-settings.
It looks working: workspace selector is working well.
Thank you guys.