title: WPF reference style in resource dictionary and use triggers
body: <p>I have a <code>Style</code> defined in a resource dictionary that applies to
  all <code>ComboBox</code> controls.  Within the <code>ComboBox</code> control, I reference the style like so:</p>
  
  <p><code>Style="{DynamicResource MyComboBoxStyle}"</code></p>
  
  <p>This works ok.</p>
  
  <p>I want to be able to add some triggers to some of the <code>ComboBox</code> controls.</p>
  
  <p>What is a good way to use the <code>Style</code> referenced as a dynamic resource yet still be able to add <code>Trigger</code>s to some of the <code>ComboBox</code> controls?</p>