Last modified: 2010-07-22 12:01:25 UTC
The enhanced editing toolbar has id="edittoolbar", which, unlike the standard #toolbar does not have the “clear” CSS property set.
That means the toolbar will appear above floating elements (way above the edit box, which clears properly) during preview. (Click Preview at the linked URL (and have the enhanced toolbar enabled in Preferences on test.)
See also bug 17021 for more issues like this.
Fixed in r53609