We must position them before the page has finished loading so that the maximum page height will become scrollable . If we position only the visible outline headings and non-outline page parts before page load, then the page will scroll only to that height. When we expand the outline, we will lose the bottom of the page off the scrollable page. Remember, Navigator is not re-drawing the page, we are . So first we position all elements tail to end, to ensure the proper page height.
Navigator creates the page height, and fits scrollbars to match, while the page loads.
Once it has loaded, new positioning will not be reflected in the scrollbars. That is, an element can easily be positioned off the page, leading to user frustration. We must, therefore, position all our elements before the page has finished loading. Navigator will correctly calculate their content height, only if they are visible. They are correctly positioned just before the page ends.