I'm trying to use jQuery UI's sortable to make list items in a browser popup window (i.e., `window.open()`, not some kind of modal) sortable.
Basically:

```
popup = window.open("", "_blank").document.body;
list = popup.appendChild(...);
$(list).sortable();

```

However, it seems like the positioning calculations within jQuery UI are getting messed up.
Dragging things around doesn't show fluid movement---nothing seems to happen, but clicking around enough will move elements all over the page (they're stuck with position: absolute styles).

Running jQuery UI sortable on the same styling/markup within the popup window itself works fine, so it seems like the issue stems from jQuery on the parent window trying to calculation positions in the child window's DOM.
Passing a container on the child DOM to jQuery UI sortable's `containment` option doesn't help.

Is there some way I can tell the parent window jQuery that it needs to be doing all of its calculations with respect to the child window's document?