Double-clicking a dock widget titlebar could make it disappear

If it wasn't already docked on a mainwindow, its state would become
unexpected.

Task-number: QTBUG-945
Reviewed-by: gabi

2 files changed, 25 insertions, 4 deletions

diff --git a/src/gui/widgets/qdockwidget.cpp b/src/gui/widgets/qdockwidget.cpp
index 6710275..a8e2a37 100644
--- a/src/gui/widgets/qdockwidget.cpp
+++ b/src/gui/widgets/qdockwidget.cpp
@@ -685,8 +685,6 @@ void QDockWidgetPrivate::_q_toggleTopLevel()
 
 void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
 {
-    Q_Q(QDockWidget);
-
     if (state != 0)
         return;
 
@@ -694,8 +692,6 @@ void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
     Q_ASSERT(win != 0);
     QMainWindowLayout *layout = qobject_cast<QMainWindowLayout*>(win->layout());
     Q_ASSERT(layout != 0);
-    if (layout->layoutState.indexOf(q).isEmpty()) //The dock widget has not been added into the main window
-        return;
     if (layout->pluggingWidget != 0) // the main window is animating a docking operation
         return;
 
@@ -1012,6 +1008,12 @@ void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect
 {
     Q_Q(QDockWidget);
 
+    if (!floating && parent) {
+        QMainWindowLayout *mwlayout = qobject_cast<QMainWindowLayout *>(q->parentWidget()->layout());
+        if (!mwlayout || mwlayout->dockWidgetArea(q) == Qt::NoDockWidgetArea)
+            return; // this dockwidget can't be redocked
+    }
+
     bool wasFloating = q->isFloating();
     bool hidden = q->isHidden();
 
diff --git a/tests/auto/qdockwidget/tst_qdockwidget.cpp b/tests/auto/qdockwidget/tst_qdockwidget.cpp
index dc67f36..e62ba8c 100644
--- a/tests/auto/qdockwidget/tst_qdockwidget.cpp
+++ b/tests/auto/qdockwidget/tst_qdockwidget.cpp
@@ -86,6 +86,7 @@ private slots:
     void visibilityChanged();
     void dockLocationChanged();
     void setTitleBarWidget();
+    void titleBarDoubleClick();
     // task specific tests:
     void task165177_deleteFocusWidget();
     void task169808_setFloating();
@@ -694,6 +695,24 @@ void tst_QDockWidget::setTitleBarWidget()
     QCOMPARE(w2.isVisible(), false);
 }
 
+void tst_QDockWidget::titleBarDoubleClick()
+{
+    QMainWindow win;
+    QDockWidget dock(&win);
+    win.show();
+    dock.setFloating(true);
+
+    QEvent e(QEvent::NonClientAreaMouseButtonDblClick);
+    QApplication::sendEvent(&dock, &e);
+    QVERIFY(dock.isFloating());
+    QCOMPARE(win.dockWidgetArea(&dock), Qt::NoDockWidgetArea);
+
+    win.addDockWidget(Qt::TopDockWidgetArea, &dock);
+    dock.setFloating(true);
+    QApplication::sendEvent(&dock, &e);
+    QVERIFY(!dock.isFloating());
+    QCOMPARE(win.dockWidgetArea(&dock), Qt::TopDockWidgetArea);
+}
 
 void tst_QDockWidget::task165177_deleteFocusWidget()
 {