Can not scroll the mouse over the blank area.

Happened in the xp sp3 ie7. If scroll over the blank area, the scrollbar
will not move. See the example 'text-content.html' I committed.
Add an empty background-image to solve this problem. It will produce an extra 'no-used' http connection(404), but I have no better idea to solve it.
$el.outerHeight() or outerWidth() retrive an incorrect value

This make the contentWidth has an smaller number. And produce an shorter scrollbar.
This is happend in xp sp3 ie7. This is perhaps caused by the 'hasLayout' problem. Add 'zoom:1' to the first child will solve the problem.