Qt4 playlist: take 2: fix segfault and other enhancements

Fix segfault when dropping more then one item onto an item in the left side selector.

Also copy instead of move items when dragging from media library to playlist and the opposite.
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

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

@@ -210,6 +210,12 @@ bool PLModel::dropMimeData( const QMimeData *data, Qt::DropAction action,
             return false;
         }
 
+        bool copy = false;
+        if( row == -1 &&
+            ( p_parent->p_input == p_playlist->p_local_category->p_input
+            || p_parent->p_input == p_playlist->p_ml_category->p_input ) )
+                copy = true;
+
         QByteArray encodedData = data->data( "vlc/playlist-item-id" );
         QDataStream stream( &encodedData, QIODevice::ReadOnly );
 
@@ -228,22 +234,27 @@ bool PLModel::dropMimeData( const QMimeData *data, Qt::DropAction action,
                 PL_UNLOCK;
                 return false;
             }
+            if( copy )
+            {
+                input_item_t *input = p_src->p_input;
+                playlist_AddExt ( p_playlist,
+                    p_src->p_input->psz_uri, p_src->p_input->psz_name,
+                    PLAYLIST_APPEND | PLAYLIST_SPREPARSE, PLAYLIST_END,
+                    input->i_duration,
+                    input->i_options, input->ppsz_options, input->optflagc,
+                    p_parent == p_playlist->p_local_category, true );
+                continue;
+            }
             if( !p_target )
             {
-                if(row == -1)
-                {
-                    playlist_TreeMove( p_playlist, p_src, p_parent, 0 );
-                }
-                else {
-                    playlist_TreeMove( p_playlist, p_src, p_parent, row );
-                }
+                if ( row == -1 ) row = p_parent->i_children;
+                playlist_TreeMove( p_playlist, p_src, p_parent, row );
             }
             else
             {
-                int i;
-                for( i = 0 ; i< p_parent->i_children ; i++ )
-                    if( p_parent->pp_children[i] == p_target ) break;
-                playlist_TreeMove( p_playlist, p_src, p_parent, i + 1 );
+                for( row = 0 ; row < p_target->p_parent->i_children ; row++ )
+                    if( p_target->p_parent->pp_children[row] == p_target ) break;
+                playlist_TreeMove( p_playlist, p_src, p_parent, row + 1 );
             }
             p_target = p_src;
         }