+ const QModelIndex proxyIndex = m_proxyModel->mapFromSource(dirIndex);
+
+ m_columns[columnIndex]->setChildUrl(childUrl);
+ columnIndex++;
+
+ ColumnWidget* column = new ColumnWidget(viewport(), this, childUrl);
+ column->setModel(model());
+ column->setRootIndex(proxyIndex);
+ column->setActive(columnIndex == lastIndex);
+
+ m_columns.append(column);
+
+ // Before invoking layoutColumns() the column must be shown. To prevent
+ // a flickering the initial geometry is set to be invisible.
+ column->setGeometry(QRect(-1, -1, 1, 1));
+ column->show();
+ layoutColumns();