The document outline viewer displays various element nodes out of order. The raw inheritance structure is correct, but the positioning of the elements (top to bottom) is off. 

This is an issue when editing big HTML or for that matter any SGML or XML document in which order is semantically relevant; because it means that you can no longer apply your own mental model of the document structure to use the outline editor for its primary purpose of document navigation/introspection.

For instance the following screenshot of a large-ish README html file shows how the <h1> element is off by 2 other elements: http://img641.imageshack.us/img641/6679/outlineoutoforder.png

Looking closer at the document reveals that the document outline editor is displaying these items “in random order” or “in alphabetical order” but rather that it has managed to display each element shifted by 2 positions, wrapping the last two elements around to appear as the first in the outline. (div id="license" is the bottom element in actual document order.)