jQuery UI Draggable Always on Top

Question

Quick question, why doesn't the appendTo option work without setting helper to 'clone'?

.draggable({ appendTo: 'body', helper: 'clone', zIndex: 2 })

will create a clone appended to the document body, but

.draggable({ appendTo: 'body', zIndex: 2 })

will not do anything. This only presents an issue in IE though because DOM order takes priority over z-index.

Does anyone have a fix other than doing this (as documented at the below url):

.draggable({ appendTo: 'body', helper: 'clone', zIndex: 1, start:  function() { $(this).toggle(); }, stop: function() { $(this).toggle(); } })

source