tree2 and the root icon

[mitroiasi]

Hi,

I have implemented a tree2 menu in my application. All works fine but I have a small problem with the icon of the root node.
The icons used also for this node are: nav-plus-line-last.gif, nav-minus-line-last.gif.
The problem is the fact that the icon has also a vertical line on top of the plus or minus sign. This shows as there is another upper node and the root node is not the first node in the hierarchy.
Is there a possibility to use another icons for the root node?