System font should override user-specified fonts when it is the redacted font

## Prerequisites
- [x] I have searched open and closed issues for duplicates.

## Describe the bug
Screenshot tool has a "Conceal text" feature. However, it doesn't work with Code text area.

### To Reproduce
Steps to reproduce the behavior:
1. Run Code, get some text in it
2. Run Screenshot
3. Check 'Conceal text'
4. Do a screenshot. It will still show visible text inside the editor.

### Expected behavior
Conceal text works as expected.

- [x] I'm using the latest version from git that I've manually compiled
- [x] I'm using the latest released stable version