Can't swtich theme on visual studio code

I am using 'code' package on arch linux and this app doesn't seem to query the themes. Whenever I click the switcher, it gets disabled. I am guessing this may be the problem:

```python
vscode_extensions_paths = ['/snap/vscode/current/usr/share/code/resources/app/extensions',
'/usr/share/code/resources/app/extensions',
str(Path.home().joinpath('.vscode', 'extensions'))]
```

As in arch linux's 'code' package the extensions are located in /usr/lib/extensions. Similarly if you use the official Microsoft's linux binaries from 'visual-studio-code-bin' package, the extensions will be located in /opt/visual-studio-code/resources/app/extensions/'.

I tried to download and modify your code to see if this works, but I can't quite figure out how how to run this app on development mode.

Start by locating the code that defines and uses `vscode_extensions_paths`, then compare its configured locations with the Arch Linux `/usr/lib/extensions` path and the `/opt/visual-studio-code/resources/app/extensions/` path. Reproduce the disabled theme switcher on Arch Linux and verify that the app can query the installed VS Code themes; the issue also notes that development-mode setup is currently unclear.

Written by the indexing model from the issue text.