Esta extensão pode ser a correta: link
Um comentário do site sobre como conseguir isso sem uma extensão:
You can avoid having to install this extension with a small tweak of your Gnome Shell Theme, found either in: ~/.themes/CustomTheme/gnome-shell/gnome-shell.css (if you're using a custom theme) /usr/share/gnome-shell/theme/gnome-shell.css (if you're using the crappy gnome/ubuntu one). Do a search for .workspace-thumbnails { You'll get two hits, go for the one that has a visible-width variable. Ex: .workspace-thumbnails { visible-width: 32px; spacing: 11px; padding: 8px; border-radius: 9px 0 0 9px; } .workspace-thumbnails:rtl { border-radius: 0 9px 9px 0; } change it visible-width from default value (32px) to something along the lines of 175px One less extension in your life.