Bug?? in tree with setViewExpanded(true) and onItemClicked

I am using the following code and there is an odd display bug in IE 6.0.0029.2180

<span id="tree1"></span>

<script>

var treeText = [ "","1","2","3","4","5","6","7","8","9","10","11","12" ];
var treeView = {0:[1],1:[5,2],2:[6,3,4],3:[7],4:[8,9,10,11,12]};

var tree = new AW.UI.Tree;
tree.setViewExpanded(true);
tree.setId("tree1");
tree.setItemText(treeText);
tree.setViewCount(function(i){return treeView[i] ? treeView[i].length : 0});
tree.setViewIndices(function(i){return treeView[i]});
tree.setCurrentItem(1);
tree.setStyle("border-color", "#BBAA99");
tree.onItemClicked = function(event, i){}
tree.refresh();

</script>

When i click on element 7 (or or sometimes when you click another number after clicking 7), an additional blank line seems to appear within the tree below element 7. I have experimented with adding more data to the second to last group and it seems to consistently happen with what ever element is last within the second to last group (container 3 in this example).

It seems to only happen when both setViewExpanded(true) and onItemClicked and only in IE as far as I can tell.

Yes, I can replicate this, so it should be a bug. I will continue investigating as I don't have the solution yet.