Type TextRow

TextRow is one row of a wrapped text: the bytes value[Start:End], where Start is a place a row can begin and End is where it stops, before the line break that ends it or, where the text wrapped, at the start of the next row. The spaces a row ends with are part of it, left hanging past the edge as a browser does, so every byte of the text but its line breaks belongs to exactly one row and a text field can put its caret on any of them.