Comment 1 for bug 595861

It is intended by me to not provide a jquery ui css file. I've found no good way to style the sortedm2m widget. The problem was just that I forgot to remove the reference from this source files.
You are really welcomed to send me a nice styling for the checkbox list currently used in the admin - or any other Idea how to improve the widget. It was a first, quick implementation to get it done.

I released 0.2.1 which just fixes this issue you described.

Still thanks for the bug report. Feel free to open new ones if you find any other issues.