Qt: add public index-from-id function to PLModel

modules/gui/qt4/components/playlist/playlist_model.cpp

@@ -385,6 +385,11 @@ QModelIndex PLModel::index( int row, int column, const QModelIndex &parent )
         return QModelIndex();
 }
 
+QModelIndex PLModel::index( int i_id, int c )
+{
+  return index( findById( rootItem, i_id ), c );
+}
+
 /* Return the index of a given item */
 QModelIndex PLModel::index( PLItem *item, int column ) const
 {

modules/gui/qt4/components/playlist/playlist_model.hpp

@@ -82,6 +82,7 @@ public:
     /* Lookups */
     QStringList selectedURIs();
     QModelIndex index( PLItem *, int c ) const;
+    QModelIndex index( int i_id, int c );
     QModelIndex currentIndex( ) { return index( currentItem, 0 ); };
     bool isCurrent( const QModelIndex &index ) const;
     int itemId( const QModelIndex &index ) const;