QTabBar: make sure the tab is repainted after releasing mouse

The tab has to be repainted even f the mouse release event happened
outside the tab bar, otherwise it will look like the tab is still
pressed.

As a drive-by, replace the repaint() call with update(); there is
no need for synchronous painting in an event handler.

Pick-to: 5.15
Fixes: QTBUG-81637
Change-Id: Ia55182be906511ac3b462f00add8a621c6c05fc3
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 38 insertions, 0 deletions

diff --git a/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp b/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
index 444a341a70..1cb6c6831f 100644
--- a/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
+++ b/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
@@ -92,6 +92,8 @@ private slots:
 
     void tabBarClicked();
     void autoHide();
+
+    void mouseReleaseOutsideTabBar();
 };
 
 // Testing get/set functions
@@ -796,5 +798,41 @@ void tst_QTabBar::autoHide()
     QVERIFY(tabBar.isVisible());
 }
 
+void tst_QTabBar::mouseReleaseOutsideTabBar()
+{
+    class RepaintChecker : public QObject
+    {
+    public:
+        bool repainted = false;
+        QRect rectToBeRepainted;
+        bool eventFilter(QObject *, QEvent *event) override
+        {
+            if (event->type() == QEvent::Paint
+                && rectToBeRepainted.contains(static_cast<QPaintEvent *>(event)->rect()))
+                repainted = true;
+            return false;
+        }
+    } repaintChecker;
+
+    QTabBar tabBar;
+    tabBar.installEventFilter(&repaintChecker);
+    tabBar.addTab("    ");
+    tabBar.addTab("    ");
+    tabBar.show();
+    if (!QTest::qWaitForWindowExposed(&tabBar))
+        QSKIP("Window failed to show, skipping test");
+
+    QRect tabRect = tabBar.tabRect(1);
+    QPoint tabCenter = tabRect.center();
+    QTest::mousePress(&tabBar, Qt::LeftButton, {}, tabCenter);
+    QTest::mouseEvent(QTest::MouseMove, &tabBar, Qt::LeftButton, {}, tabCenter + QPoint(tabCenter.x(), tabCenter.y() + tabRect.height()));
+
+    // make sure the holding tab is repainted after releasing the mouse
+    repaintChecker.repainted = false;
+    repaintChecker.rectToBeRepainted = tabRect;
+    QTest::mouseRelease(&tabBar, Qt::LeftButton, {}, tabCenter + QPoint(tabCenter.x(), tabCenter.y() + tabRect.height()));
+    QTRY_VERIFY(repaintChecker.repainted);
+}
+
 QTEST_MAIN(tst_QTabBar)
 #include "tst_qtabbar.moc"