Content height equals scrollable div height

I observed that if the height of the content of a scrollable vertical div exactly matches the height of the div, the scroll bar will show up. I bumped the height of the scrollable div up by one and the scroll bar went away.

Have you tested this case? I saw it under FireFox 19.0.2.

http://ww.wp.xz.cn/extend/plugins/wp-jscrollpane/