KExtraColumnsProxyModel: fix bug in sibling() which broke e.g. selections

autotests/kextracolumnsproxymodeltest.cpp

@@ -170,6 +170,9 @@ private Q_SLOTS:
         QVERIFY(indexToText(pm.index(0, 5)).startsWith("0,5,"));
         QCOMPARE(indexToText(pm.index(0, 5, secondParent).parent()), indexToText(secondParent));
 
+        QCOMPARE(pm.index(0, 0).sibling(0, 4).column(), 4);
+        QCOMPARE(pm.index(0, 4).sibling(0, 1).column(), 1);
+
         QVERIFY(!pm.canFetchMore(QModelIndex()));
     }
 
@@ -304,15 +307,28 @@ private Q_SLOTS:
         // And a QSFPM underneath
         QSortFilterProxyModel proxy;
         proxy.setSourceModel(&mod);
+        QCOMPARE(proxy.columnCount(), 4);
         pm.setSourceModel(&proxy);
+        QCOMPARE(pm.columnCount(), 6);
+        QCOMPARE(extractRowTexts(&pm, 0), QString("ABCDZ0"));
         // And a selection
         QItemSelectionModel selection(&pm);
         selection.select(pm.index(0, 0), QItemSelectionModel::Select | QItemSelectionModel::Rows);
+        const QModelIndexList lst = selection.selectedIndexes();
+        QCOMPARE(lst.count(), 6);
+        for (int col = 0; col < lst.count(); ++col) {
+            QCOMPARE(lst.at(col).row(), 0);
+            QCOMPARE(lst.at(col).column(), col);
+        }
 
         // When sorting
         pm.sort(0, Qt::DescendingOrder);
+
+        // Then the proxy should be sorted
         QCOMPARE(extractRowTexts(&pm, 0), QString("EFGHZ0"));
         QCOMPARE(extractRowTexts(&pm, 1), QString("ABCDZ1"));
+        // And the selection should be updated accordingly
+        QCOMPARE(selection.selectedIndexes().first().row(), 1);
     }
 
 private:

src/kextracolumnsproxymodel.cpp

@@ -39,7 +39,7 @@ public:
     // Configuration (doesn't change once source model is plugged in)
     QVector<QString> m_extraHeaders;
 
-    // for layoutAboutToChanged/layoutChanged
+    // for layoutAboutToBeChanged/layoutChanged
     QVector<QPersistentModelIndex> layoutChangePersistentIndexes;
     QVector<int> layoutChangeProxyColumns;
     QModelIndexList proxyIndexes;
@@ -117,10 +117,10 @@ QModelIndex KExtraColumnsProxyModel::mapToSource(const QModelIndex &proxyIndex)
 
 QModelIndex KExtraColumnsProxyModel::sibling(int row, int column, const QModelIndex &idx) const
 {
-    if (idx.column() >= sourceModel()->columnCount()) {
-        return index(row, column, parent(idx));
+    if (row == idx.row() && column == idx.column()) {
+        return idx;
     }
-    return mapFromSource(sourceModel()->sibling(row, column, mapToSource(idx)));
+    return index(row, column, parent(idx));
 }
 
 QItemSelection KExtraColumnsProxyModel::mapSelectionToSource(const QItemSelection &selection) const