Prioritizing the visibility of all of those checkbox settings (highlight all, match case, etc.) over the visibility of matches makes no sense. Obviously, it isn't an issue when your screen is full-sized. But it's hidden if, for whatever reason, your window is taking up less than 2/3 of the screen (i.e., split screen).
Most people want to see the number of results and keep track of where they are (e.g., "2 of 278 matches"). I highly doubt people's checkbox settings regularly change, but the number of matches and how far along you are does. So logic follows that the matches should always be visible.