我正在运行 Ubuntu 18.04，没有任何桌面调整或附加组件。不知何故，我按错了热键，结果只能看到第二个空白工作区和右侧的栏。我该如何摆脱它？
编辑
我没有（明确）安装任何扩展：
paul@paul-desktop:~$ ls -al ~/.local/share/gnome-shell/extensions
ls: cannot access '/home/paul/.local/share/gnome-shell/extensions': No such file or directory
paul@paul-desktop:~$ ls -al /usr/share/gnome-shell/extensions
total 16
drwxr-xr-x 4 root root 4096 Aug 5 2019 .
drwxr-xr-x 6 root root 4096 Jan 23 02:09 ..
drwxr-xr-x 3 root root 4096 Aug 5 2019 [email protected]
drwxr-xr-x 3 root root 4096 Aug 5 2019 [email protected]