Problem with treeview occured in IE

[ghost]

Today, I had to face a problem with treeview that occured in IE. Unfortunately the tree does not appear like it should for example in Firefox or Safari.

Finally I've found a solution in using the old syntax of prototype to add a html-class to an element in prototype.treeview.js -> render: function():
addClassName(element, className) -> HTMLElement (see prototype api)

That fixes the treeview for IE. At least, it works for me :-) Greetings.