Hello,
  A couple of (hopefully correct) observations on Position.absolutize:
    - if you set position to absolute in a css class, rather then by
      using  the style property, the check (element.style.position =     
''absolute'') will fail.
    - the width css property on an element does not include padding,
      but $(''el'').clientWidth and clientHeight do. So when
calling
      absolutize on an element, the size will be increased by the
      padding.
  I really don''t know how(if) these problems can be mitigated,
nevertheless I think they should at least be included in the
documentation.
P.S. I wanted to search for tickets regarding this issue but the
javascript bugs report on the rubyonrails trac page is broken.
(http://dev.rubyonrails.org/report/21).