Scrollbar detection

Shrink and resize the window, see how scrollbars are detected when present,
this gives us the nice ability to detect hidden content, horizontally or vertically.

The coloured blocks in the Horizontal and Vertical Scrollbar status lines are:
Green block for hidden or inactive bars, Red block for visible and active bars.

MSIE, by default, display a vertical ghosted scrollbar on the left each page,
even if no content is actually hidden, a placeholder for the vertical scrollbar.

Status: