Do not crash when double-clicking a tab in a QTabBar with movable tabs

Check if QTabBarPrivate's movingTab member is 0 before dereferencing it.
This fixes a crash when double-clicking a tab. New unit test included.

http://bugs.kde.org/show_bug.cgi?id=202767

Reviewed-by: Olivier Goffart <ogoffart@trolltech.com>
Merge-Request: 1337

2 files changed, 36 insertions, 1 deletions

diff --git a/src/gui/widgets/qtabbar.cpp b/src/gui/widgets/qtabbar.cpp
index 5166390..d8246c8 100644
--- a/src/gui/widgets/qtabbar.cpp
+++ b/src/gui/widgets/qtabbar.cpp
@@ -1836,7 +1836,8 @@ void QTabBarPrivate::moveTabFinished(int index)
     }
 #endif //QT_NO_ANIMATION
     if (allAnimationsFinished && cleanup) {
-        movingTab->setVisible(false); // We might not get a mouse release
+        if(movingTab)
+            movingTab->setVisible(false); // We might not get a mouse release
         for (int i = 0; i < tabList.count(); ++i) {
             tabList[i].dragOffset = 0;
         }
diff --git a/tests/auto/qtabbar/tst_qtabbar.cpp b/tests/auto/qtabbar/tst_qtabbar.cpp
index 041836c..3f77b7a 100644
--- a/tests/auto/qtabbar/tst_qtabbar.cpp
+++ b/tests/auto/qtabbar/tst_qtabbar.cpp
@@ -94,6 +94,7 @@ private slots:
     void moveTab();
 
     void task251184_removeTab();
+    void changeTitleWhileDoubleClickingTab();
 };
 
 // Testing get/set functions
@@ -535,5 +536,38 @@ void tst_QTabBar::task251184_removeTab()
 }
 
 
+class TitleChangeTabBar : public QTabBar
+{
+    Q_OBJECT
+
+    QTimer timer;
+    int count;
+
+public:
+    TitleChangeTabBar(QWidget * parent = 0) : QTabBar(parent), count(0)
+    {
+        setMovable(true);
+        addTab("0");
+        connect(&timer, SIGNAL(timeout()), this, SLOT(updateTabText()));
+        timer.start(1);
+    }
+
+public slots:
+    void updateTabText()
+    {
+        count++;
+        setTabText(0, QString("%1").arg(count));
+    }
+};
+
+void tst_QTabBar::changeTitleWhileDoubleClickingTab()
+{
+    TitleChangeTabBar bar;
+    QPoint tabPos = bar.tabRect(0).center();
+
+    for(int i=0; i < 10; i++)
+        QTest::mouseDClick(&bar, Qt::LeftButton, 0, tabPos);
+}
+
 QTEST_MAIN(tst_QTabBar)
 #include "tst_qtabbar.moc"