Place draggable boxes in grid.


I have 3 draggable boxes, wich default horizontal positioned.

<div id="a" class="box_a" style="cursor:move">A</div>
  <%= draggable_element :a%>

<div id="b" class="box_b" style="cursor:move">B</div>
  <%= draggable_element :b%>

<div id="c" class="box_c" style="cursor:move">C</div>
  <%= draggable_element :c %>

The boxes can me move arround on the homepage.

I also want to realize:

a)The boxes must be in a defined grid (div)
b)The boxes interact together, so when i drag box A to box B, Box B
moves up to another space in the grid.

Example > see Modules..

Someone links/examples???

Thanks in advance...