Optional
Readonly
Where the caret's line is held, as a fraction of the scrolling area's height. 0.5 is dead centre; 0.4 sits it slightly above, which most people find easier to read from.
The scrolling element; the window by default.
Where the caret's line is held, as a fraction of the scrolling area's height. 0.5 is dead centre; 0.4 sits it slightly above, which most people find easier to read from.