title: How to make ScrollView's content transparent
body: <p>In Interface Builder I have this hierarchy:</p>
  
  <ol>
  <li><p>View</p>
  
  <p>1.1 Image View //it's my background</p>
  
  <p>1.2 Scroll View</p>
  
  <p>1.2.1 Image View (added as subview to ScrollView above) //here I have image with transparent background</p></li>
  </ol>
  
  <p>What I'm trying to achieve is to see my background image behind scrollview's image. Now it doesnt work - background of scrollview is black and I don't see background. I was trying with setting off opaque but it didn't help. I have set background on every control to "clear color". I'm out of ideas. Anybody knows how to set values on every element?</p>