First, I'm sorry for there being no cursor/selection for now, I'm really lazy XD
To use the explanation menu, you click the characters on the top line.
It isn't evident, but clicking on two of them adds a range to your explanation.
From there, you can click the buttons to move it up/down or delete it, and the comment
also automatically gets focused.
Also, you can use the golf input to measure how long your code is, and to just highlight it.
Type in your golfed code in the input box below. It will be highlighted.
Your code is 0 characters long and 0 UTF-8
bytes long.
Since the code you input is a one-liner, we'll let you write an explanation.