 given by <code>textDirection</code>.</p>
<p>The fields 'textSelectionBase' and 'textSelectionExtent' describe the
currently selected text within <code>value</code>.</p>
<p>For scrollable nodes <code>scrollPosition</code> describes the current scroll
position in logical pixel. <code>scrollExtentMax</code> and <code>scrollExtentMin</code>
describe the maximum and minimum in-rage values that <code>scrollPosition</code> can
be. Both or either may be infinity to indicate unbound scrolling. The
value for <code>s