ComboBox on RollOver

Hi,
I have a combo displaying all Fonts available on the users system.
On click, a text field shows the selected item, the Font's name and the item is displayed in the selected font. This works fine.

ComListenerB.change = function(){
var obj = myComboB.selectedItem;
showFont.text = obj.label;
myformatFont = new TextFormat();
myformatFont.color = 0x666666;
myformatFont.font = obj.label;
myformatFont.size = 10;
myformatFont.align = "center";
showFont.setTextFormat(myformatFont);
//xx
myComboB.addEventListener("change", ComListenerB);

I would like to have the same action already on RollOver, so the client can see, which Font he is going to select.

ComListenerB.itemRollOver = function(evt:Object){
//>>put the same code here as above
//but does not work??

myComboB.addEventListener("itemRollOver", ComListenerB);

Thank you for your help.
Luciewong