title: GUI of Unity 4.6 - Detecting On Click() Down
body: <p>I'm using the GUI of Unity 4.6 beta and I need to detect the "On Click() Down" similar to "Mouse Down". The default is mouse up.</p>
  
  <p><img src="https://i.stack.imgur.com/1PLdv.png" alt="&quot;"></p>
  
  <p>Thanks!</p>