title: Making a circular NSSlide look and behave like in GarageBand
body: <p>I am new to drawing with Cocoa, and I am making some software which will have sliders similar to these found in GarageBand:</p>
  
  <p><a href="http://img33.imageshack.us/img33/2668/schermafbeelding2010061r.png" rel="nofollow noreferrer">GB Sliders http://img33.imageshack.us/img33/2668/schermafbeelding2010061r.png</a></p>
  
  <p>These look beautiful and can be controld by moving the mouse up and down.</p>
  
  <p>Can you help me with customizing NSSliders by subclassing them, so I can make them look and behave exactly as in GarageBand? Thanks.</p>
  
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  <p>I have one image for the knob which should be rotated as they do not need to be in 3D .</p>