[jQuery] [treeview] top node (root) is open but has plus sign????

I have a treeview where there is only one node at the top of the tree
with several child nodes -- some having child nodes -- some not. All
open / close indicators are as expected EXCEPT the very top one which
even though the node is open it show a '+' sign rather than a '-' sign
which is the normal display for an open node. Also clicking this top
node's '+' closes the whole list AND changes the indicator to a '-'
sign. Again, not what you would expect.

Any ideas?