Can not drop item in between 2 columns (element instead snaps inside one another)

[RensTillmann]

Hi, to explain what I mean I made this bin: http://jsbin.com/pagijuxiju/edit?html,css,js,output

Try to drag and drop the green item between the orange and purple column.
You will see that it basically isn't possible, because it will snap inside one another.

It is possible to achieve this by dragging the purple column to the bottom. So it's kind of possible but at the moment not really user friendly, I was wondering if there is a work around for this problem. Thanks!

[owen-m1]

Supported in 1.8.0: http://sortablejs.github.io/Sortable/#nested