Created two droppable divs, absolute positioned (one on left and on on right of the page). Create two draggables.

When dragging the draggable from right to left on the page, the helper appears to go behind the right div.

Test:

            $(function() {
                $('#container-9 ul').tabs({ disabled: [3], fxFade: true, fxFade: true, fxSpeed: 'fast', cache: true });
                $('<p><a href="#">Remove 2nd tab (error: you cannot switch to tab 4)<\/a><\/p>').prependTo('#fragment-22').find('a').click(function() {
                    $('#container-9 ul').tabsRemove(2);
                    return false;
                });
                $('<p><a href="#">Add new tab<\/a><\/p>').prependTo('#fragment-22').find('a').click(function() {
                    $('#container-9 ul').tabsAdd('test3.html','tab 4');
                    return false;
                });
                $('<p><a href="#">Remove 2nd tab<\/a><\/p>').prependTo('#fragment-22').find('a').click(function() {
                    $('#container-9 ul').tabsRemove(2);
                    return false;
                });
                $('<p><a href="#">Add 2 tabs<\/a><\/p>').prependTo('#fragment-22').find('a').click(function() {
                    $('#container-9 ul').tabsAdd('test1.html','tab 2');
                    $('#container-9 ul').tabsAdd('test2.html','tab 3');
                    return false;
                });
            });

Tried to use UI/Selectables for my project and identified some mjaor shortcomings:

1. If you shrink your selection rectangle after some elements has been marked as selected (".ui-selecting"), those elements will become selected (".ui-selected"). Screenshot attached.

2. If you drag the selection frame to fast, those elements won't become selected. Relates to ​http://dev.jquery.com/ticket/1645

3. Some other things i would like to see: Deselect selection with click on parent, select/deselect via mouseclick and keyboards modifiers

All of this can be reproduced with the orginal demo: ​http://dev.jquery.com/view/trunk/ui/current/demos/ui.selectable.html