Font color combobox

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C#

Silverlight

Hi,
I want to learn how to put image inside font color/highlight color combobox's header , for example, like the ones in Microsoft Office Word for font color and highlight color combobox? or are they somewhat complex comboboxes( with buttons, colomns..)
I created simple combobox with colored Rectangles
as items, when you select a color (textbox), it will be applyed on selected text and the selected rectangle will be shown in the header of the the combobox
I just want the apperiance of the font color combobox like the one in Microsoft Office Word, how to do this?
(Sorry for my English!)

part of Xaml :

<local:mycombobox name="MyFColorComoB" hieght="26" width="40" prekeydown="MyFColorCB_PreKeyDown" xmlns:local="#unknown">

<comboboxitem>
<rectangle width="20" stroke="Black" height="20" fill="LightGray" />
</comboboxitem>

<comboboxitem>
<rectangle width="20" stroke="Black" height="20" fill="Orange" />
</comboboxitem></code>

</local:mycombobox>