This quick tutorial is going to show Gnome Desktop beginners how to enable the ‘Shell theme’ drop-down box in the Gnome Tweak Tool.

A Gnome Shell theme changes shell buttons, colors, panels, etc. The setting is disabled by default in Gnome Tweak Tool, and you’ll see the prompt “Shell user-theme extension not enabled” when you hover the cursor over the alert icon.

As it prompts, you need to enable user-theme extension. While it’s not available by default, install it via following steps:

1. Open Firefox web browser and go to https://extensions.gnome.org:

Click the link text “click here to install browser extension” and follow the pop-ups to install the browser extension:

2. After that, refresh the web page, if you get an error prompt that “native host connector is not detected“,

then open terminal via Ctrl+Alt+T and run command:

sudo apt install chrome-gnome-shell

3. Finally go to https://extensions.gnome.org/extension/19/user-themes/.

Click the switch to turn on and then select install the Gnome Shell extension:

After all, restart Gnome Tweak Tool and you’ll see the Shell theme drop-down box enabled after enabled the User Themes extension.