Combo rendering problem

Referring to the grid.htm example in the examples\quickref folder, when I insert the following code:
var cb = new AW.UI.Combo;
cb.setItemText(["test", "test2", "test3"]);
cb.setItemCount(3);
obj.setCellTemplate(cb, 1); // column-1

There seems to be rendering problem with the combo, on first click, the row cursor selector is shown, however on subsequent click of the combo, the cursor selector is not shown and I have to guess which item I am going to select. I test with AW beta 1, it doesn't seem to have this issue, but beta 2 have this problem. Am I doing something wrong or it could be due to some fix to the popup frame/combo control in the beta2 release?

Thanks for any pointers.