WPF combo box Image as tooltip

Question

Dear friends,

I am creating a WPF application which contains a combobox.When there is a mouse over on the combo box, suppose the combo contains the strings apple and orange, I need to show the corresponding image as a tooltip.

I got a sample application from the following link.

http://diptimayapatra.wordpress.com/2010/03/05/image-in-tooltip-in-wpf/

I understood the code behind, but there are some doubts in xaml portion. How can we use the ItemsPanelTemplate? Where I need to place these portion?

I tried the following...

<Window>
<Styles...>
</Styles>
       <Grid> 
            <ItemPanelTemplate....>
            </ItemPanelTemplate>
            <Listbox>
            </Listbox>
...

</Window>

But I can't. I am a beginer in WPF.Please help.