In D29107#655102, @dfaure wrote:

You say "The format does not seem to exist before the first character" and yet that's exactly where you're moving the cursor.
The code looks ok to me, but the comment is confusing/wrong.

Fair point. I've just copied the comment from the old code, without much thinking about it.

It's just about setting the format of the cursor from the first char. I agree that it's probably a bug that setDocument doesn't trigger that, but I'm not sure the old bug report reference still makes sense here, it feels like a different issue to me (the comment and old workaround says "there's nothing at pos 0, go to pos 1 to grab the format"). Unrelated to your issue and fix.

I think actually that the comment was about the same issue, but the author actually misinterpreted it. When we're going to pos 1 to grab the format, we are still grabbing it from the very first character and very first block in the document. The moveCursor(Start) does it too.

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This is freshly opened document without the patch (note the font size is 10 and bold is not marked, although the first symbol is of size 20 and is bold):

This is what happens if I more cursor to the right (the cursor is not visible, but it's at pos 1, at it grabbed style from the first symbol: it's bold and of size 20. I can now freely move it back to the left, and the style will be preserved. That's the old workaround):

And that's the screenshot with this patch (which doesn't move it to the pos 1, but to the start; the cursor is adjusted from the very beginning):