Could a keyboard shortcut be add to db<>fiddle that would let us comment-out multiple lines of SQL at a time?
Similar to `CTRL+/` in SQL Developer.
You can now use `Ctrl+/` (`Cmd+/` on MacOS) to toggle comments on selected lines.
This was just a case of manually implementing the built-in feature of CodeMirror from their [default keymap](https://codemirror.net/docs/ref/#commands.defaultKeymap) the same as done previously for indentation with `Ctrl+[` etc. I think implementing the whole default keymap is a bit over the top, preferring the more minimal [standard keymap](https://codemirror.net/docs/ref/#commands.standardKeymap).
The only issue is that it's not very discoverable.