title: WPF combobox with image in case of null value
body: <p>I would like to have a combobox in WPF whose items are of type string (like the default). The only difference is that I want to display an image (error) if the string is x:null. Anyone an idea how I can create an itemtemplate or style to display an image in the case of a null (or empty) string and the string in all other cases in the combobox.</p>
  
  <p>Thanks!</p>
  
  <p>-- Carsten</p>