Thank you, Kovid. That is all I wished. So I will be able to change wrapping on the fly.
That is because I often have to modify epub resulting by export from Indesign, and I want to beautify, to clean the ugly code got by Indesign. Often classes or other attibutes are in the beginning of <p> tags, and so the text I want to clean is at the beginnig of each line.
When wrap is on I see all the <p> text but the structure of the file is hide, when it is off I see only the text I want to clean, and file structure is visible.
Still thank you.