all the themes by default build for ltr. for using in rtl website i need to edit the themes files..

I have used the following hack in order to customise the placeholder that Sortable uses:

$(selector).sortable({
  placeholder: {
    element: function(currentItem) {
    },
    update: function(container,p) {
    }
  }
});

This hack works in all versions of UI since 1.7.2 - the one I'm using. I got the hack from StackOverflow here:

​http://stackoverflow.com/questions/2150002/jquery-ui-sortable-how-can-i-change-the-appearance-of-the-placeholder-object

This is actually extremely useful in a variety of situations and I think it should be officially part of the API. I would suggest tweaks to this: the currentItem, for example, is not the ui.item we get in other functions. So, a bit of tweaking of the interface would be needed, but this is so amazingly useful I think it would be worth it.

I found a (brief!) discussion on whether dropOnEmpty should exist on Sortable. The answer was no.

It is useful; but it's the wrong way around. Currently in order to prevent a connected Draggable from being dropped on an empty sortable you have to disable the sortable whenever it becomes empty and re-enable it if it gains content (on the theory that drag+drop is not the only way of creating DOM content).

I would propose that dropOnEmpty should apply to the sortable itself, as to whether it will accept a droppable if it is empty; rather than whether its own items can be dropped onto empty others.

Alternatively, the options to Draggable should have a dropOnEmpty that does the same thing as Sortable's; i.e. prevents this draggable being dropped on an empty sortable.

The former, while preferable in my mind, has the disadvantage of not being backward-compatible.