title: how to limit seekbar
body: <p>I'd like to set max and minimum limits of <strong>SeekBar</strong> to 50 and 20 respectively.</p>
  
  <p><a href="http://developer.android.com/reference/android/widget/SeekBar.html" rel="noreferrer">SeekBar</a> has a direct option top provide max value, but how to set its minimum value to 20 rather than 0?</p>