ildrenInHitTestOrder</code> and <code>childrenInTraversalOrder</code> must be
empty.</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>scrollPosition</code> can (temporarily) be outside this range, for
example during 