What does DrRacket mean by reverse video in the definition window (after clicking "Run")?

Question

I wrote a small module in the language of novice students. When I click Run, some of the expressions in the Definitions window are highlighted in the reverse video (red text on a black background). I can't figure out which expressions are selected or what the reverse video means.

Answer 1

In accordance with color preferences, he indicates a code that the tests did not cover: