nsIXULSortService in Firefox 3.0

 Sort the contents of the widget containing <code>aNode</code>
 using <code>aSortKey</code> as the comparison key, and
 <code>aSortDirection</code> as the direction.

 @param aNode A node in the XUL widget whose children are to be sorted.
 @param aSortKey The value to be used as the comparison key.
 @param aSortDirection May be either <b>natural</b> to return
 the contents to their natural (unsorted) order,
 <b>ascending</b> to sort the contents in ascending order, or
 <b>descending</b> to sort the contents in descending order.