protected void onRender(MarkupStream markupStream)
{
super.onRender(markupStream);
dropOptions.put("onDrop", new JavascriptFunction("function(draggable, droppable, event) { wicketAjaxGet('" + onDropBehavior.getCallbackUrl()
+ "&id=' + draggable.id); }"));
JavascriptBuilder builder = new JavascriptBuilder();
builder.addLine("Droppables.add('" + getMarkupId() + "', ");
builder.addOptions(dropOptions);