if we define the following CCS to fix the height of the suggestion list, the list will become to be scrollable when it is overflow, for example, there are 100 suggestions should be shown.
if a user moves his mouse to the scroll bar, the suggestion list will disappear immediately in IE6/7 but in FF. The reason is that the onblur event of the text field is triggered in IE but in FF. At the moment the mouse pointing to the scroll bar, Wicket.AutoComplete.mouseactive is 0, therefore, hideAutoComplete() was called. That's why the suggestion list disappeared in IE6/7.