Sortable - placeholder

Sortable - placeholder


I hope this isn't a dumb question ...
Is there a way of limiting where the placeholder can appear? I have a
magazine layout app and I only want users to be able to drop pages
onto spreads, and to move whole spreads. I don't want them to be able
to drop a page onto the layout for example, nor layouts onto other
layouts - and while I can deal with it through update: or stop: and
take it away, it would be neater if they were never given the option.
I am sure there is some very obvious thing I am not doing ...
Many thanks for your help so far - as someone pretty new to Jquery I
find this board and the sister ones absolutely priceless - thanks
Ben
(this is the sort of thing I had in mind ...)
<ol class="layout">
<li id="spread_1" class="spread">
<ol>
<li id="page_1" class="page"><img src=" jpeg of p1" /></li>
<li id="page_2" class="page"><img src=" jpeg of p2" /></li>
</ol>
</li>
<li id="spread_2" class="spread">
<ol>
<li id="page_3" class="page"><img src=" jpeg of p3" /></li>
<li id="page_4" class="page"><img src=" jpeg of p4" /></li>
</ol>
</li>
....
</ol>
<ul class="workspace"> // just a temp holding place so users can drop
a page here and pick it up later//
<li id="page_5" class="page"><img src=" jpeg of p5" /></li>
</ul>