title: Clear wpf listbox selection using button in control template and no codebehind
body: <p>I want to create a <code>Style</code> for a WPF <code>ListBox</code> that includes a <code>Button</code> in the <code>ControlTemplate</code> that the user can click on and it clears the <code>ListBox</code> selection. 
  I dont want to use codebehind so that this <code>Style</code> can be applied to any <code>ListBox</code>.
  I have tried using <code>EventTrigger</code>s and <code>Storyboard</code>s and it has proved problematic as it only works first time and stopping the <code>Storyboard</code> sets the previous selection back.
  I know I could use a user control but I want to know if it is possible to achieve this using only a <code>Style</code>.</p>