title: QML: Update a nested ListView
body: <p>I'm making a TV-Guide on Sailfish OS, and have met an - for now - obstacle.
  As I want to have the possiblity to mark each entry for a customized list
  I need to modify the model behind. I have tried modifying the model directly: 
  <code>model.favorite = true</code> but that doesn't work. I have tried to modify the underlying
  <code>arrayOfObjects</code>, but that isn't reflected in the UI, and I can't trigger an update because I can't access the ListView. I have tried to make a customized model, but since I can't reference it's instance, to no avail.</p>
  
  <p>Below is a very simplified representation of the layout using mostly basic QML.</p>
  
  <pre><code>Page {
      Flickable {
          Column {
              SlideshowView { // PathView
                  model: arrayOfObjects
                  delegate: channelDelegate
              }
          }
      }
  
      Component {
          id: channelDelegate
          ListView {
              id: channelList
              // ProgramModel just iterates thru arrayOfObjects and appends them
              model: ProgramModel {
                  programs: arrayOfObjects
              }
              delegate: programDelegate
              Component.onCompleted: {
                  // I can't reference channelList from here.
              }
          }
      }
  
      Component {
          id: programDelegate
          ListItem {
              Button {
                  onClicked: {
                      // How do I reference channelList?
                      // Doing it by name doesn't work.
                  }
              }
          }
      }
  }
  </code></pre>
  
  <p>I have tried calling ApplicationWindow (which works), to send a signal that I connect to
  in channelList.onCompleted (which also works), but since I can't reference the list from 
  there it doesn't help.</p>
  
  <p>I'm on QT 5.6 so some solutions may not work. 
  And I would really prefer keeping it pure QML; no C++.</p>