[GeoffR]

There is some funky stuff happening when I change the line spacing and margins from the Aa menu in an ePub book. A picture briefly flashes on the screen, it is too fast to say exactly what it is a picture of, but it is not a picture from the current book and I don't recognise it. I think it is a photo of a person, but I can only see the top of the head as the rest is obscured by the menu.

It doesn't seem to cause any problem, but it is a bit weird.

Edit: Actually after looking at it a few more times I think the picture could be a section of the book's cover, so maybe it is just something to do with the re-rendering of the book after the settings have changed.