Caret Bug Demo

This only works in Internet Explorer. Check out Google's cache of this page to see this bug in action, under slightly different conditions (well, HTML code). Work-arounds can be found in the Frost Jedi Graemlin Creator JavaScript Additions and in this phpBB mod. A more complete description of the problem follows:

Although this demonstration requires the use of two JavaScript objects that are exclusive to MSIE - Selection and TextRange - the bug that it exploits is only in the TextRange object. An example of this bug that doesn't involve the Selection object can be found in phpBB. To reproduce the bug there, do the following:

Go to the page you normally would to make a new post or a new reply.
Type in some text, and highlight it.
Unhighlight that text by selecting text within the highlight.
Try to insert an emoticon. It'll appear at the top of the page.

vBulletin overcomes this bug by redetermining the TextRange every time an emoticon would be inserted. The problem with this work-around is that if you select outisde of the textarea, the TextRange is reset. The Frost Jedi Graemlin Creator overcomes this problem by resetting the TextRange only when the bug would occur - only when the current boudingHeight and the boundingHeight of a previously created TextRange object don't match.