Scrolls one page up so that the first line (truncated or whole)
of the current page becomes the fully visible last line.
<p>
The caret is scrolled the same number of lines so that its location
relative to the top line remains the same. The exception is the beginning
of the text where a full page scroll is not possible. In this case the
caret is moved in front of the first character.
</p><p>
Adjusts the selection according to the caret change. This can either add
to or subtract from the old selection, depending on the previous selection
direction.
</p>
Scrolls one page up so that the first line (truncated or whole) of the current page becomes the fully visible last line. <p> The caret is scrolled the same number of lines so that its location relative to the top line remains the same. The exception is the beginning of the text where a full page scroll is not possible. In this case the caret is moved in front of the first character. </p><p> Adjusts the selection according to the caret change. This can either add to or subtract from the old selection, depending on the previous selection direction. </p>