## Clearing highlights

### User Request

As a user, I want to be able to highlight an entire note and click the highlight button to remove any/all highlights.

### Issue Description

- If I have rule lines, it doesn't clear the highlights - it only adds them to everything.
- If I highlight everything in one colour and then try and unhighlight, it doesn't clear.
- I have to pick sections by hand and unhighlight piecemeal, which is time-consuming and a faff.