Fix a crash on the focus chain when removing items from the scene.

The crash was because of the dangling pointer set on the tabFocusFirst
attribute in QGraphicsScene. A child which was the tabFocusFirst was
removed from the scene and fixFocusChainBeforeReparenting was setting the
new tabFocusFirst pointer to the parent (since in that example it was
the focusNext) but later on the parent was removed also from the scene
(due to the recursion of removeItem if you call it with the parent :
first children, then the parent itself) and
fixFocusChainBeforeReparenting was not called again so if you delete
the parent then the scene has the dangling pointer set.

Task-number:QTBUG-6544
Reviewed-by:janarve

1 files changed, 32 insertions, 0 deletions

diff --git a/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp b/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
index 3303df5..a835259 100644
--- a/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
+++ b/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
@@ -168,6 +168,7 @@ private slots:
     void task236127_bspTreeIndexFails();
     void task243004_setStyleCrash();
     void task250119_shortcutContext();
+    void QT_BUG_6544_tabFocusFirstUnsetWhenRemovingItems();
 };
 
 
@@ -2855,6 +2856,37 @@ void tst_QGraphicsWidget::polishEvent2()
     QVERIFY(widget->events.contains(QEvent::Polish));
 }
 
+void tst_QGraphicsWidget::QT_BUG_6544_tabFocusFirstUnsetWhenRemovingItems()
+{
+    QGraphicsScene scene;
+    QGraphicsWidget* parent1 = new QGraphicsWidget;
+    QGraphicsWidget* child1_0 = new QGraphicsWidget;
+    QGraphicsWidget* child1_1 = new QGraphicsWidget;
+
+    QGraphicsWidget* parent2 = new QGraphicsWidget;
+
+    // Add the parent and child to the scene.
+    scene.addItem(parent1);
+    child1_0->setParentItem(parent1);
+    child1_1->setParentItem(parent1);
+
+    // Hide and show the child.
+    child1_0->setParentItem(NULL);
+    scene.removeItem(child1_0);
+
+    // Remove parent from the scene.
+    scene.removeItem(parent1);
+
+    delete child1_0;
+    delete child1_1;
+    delete parent1;
+
+    // Add an item into the scene.
+    scene.addItem(parent2);
+
+    //This should not crash
+}
+
 QTEST_MAIN(tst_QGraphicsWidget)
 #include "tst_qgraphicswidget.moc"