UI effects wrapper div weird behavior

Hi all,
I've come upon this yesterday. I was trying to apply the .hide
('slide') effect and unexpected results emerged.
See the test-case here: http://jsbin.com/areku
I filed a ticket as well: http://dev.jqueryui.com/ticket/4770
Seems that the .ui-effects-wrapper isn't friend with auto margins and
width set in percents.
--
Bohdan Ganicky