Combo box check box object

Question

Hi,

I have a combobox whose itemstemplate is a check box whos itemsource is a collection of objects, say a Person.

Each person has a name and so this will be the checkboxes content.

However now I want to find out which checkbox in the comboboxs' collection is checked, though when I call - (this.MainComboBox.Item[i] as CheckBox).IsChecked  - fails because there is "no" check box.

How do I access the IsChecked property of the items in the combobox given that the item source is a collection on objects?

Thanks greatly in advance.

Person.