jQuery sortables - nested helper

I have two jQuery scripts on jsFiddle:

• http://jsfiddle.net/9uhfX/14/
• http://jsfiddle.net/9uhfX/15/

First one

The first one is how I want it to look. Nesting list el开发者_运维问答ements with nesting sorting functions. This one does not work with puting the list elements inside other list elements.

Second one

The second one contains a min-height and here it works with puting list elements inside other list elements.

The question

Is it possible to add the dropzone (helper?) inside the list element instead of out in the ul, to make it not look like the second example. Define an own drop area?

I might want all dropable areas visible from start.

Anything that might make this drag drop easier and more beautiful are welome.

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There is a already a own drop-area, the empty ul-elements. To make it look "better" use a different background for ul(for example "inherit"):

http://jsfiddle.net/doktormolle/9uhfX/18/