Text Edit example with wrong heading behavior

I was using the Text Edit example to learn about QTextEdit, and noticed that the heading behavior seems wrong in one case.

1. Add a new line.
2. Select the style "Heading 3".
3. Select the whole line and remove it (but keep the line break, i.e. don't change the line count of the document).
4. Enter some text.

Notice that after step 4, the heading is entered with the heading level expected, but the bold format isn't kept.
This happens whenever we create a new heading. But with headings loaded from an HTML file, this doesn't happen.