Fix QDockWidget being unable to dock when initially floating.

When setFloating(true) is called before show, frame strut events
are not enabled for the native window (since there is none yet)
in QDockWidgetPrivate::setWindowState(). In that case, do
it in the show event handling.

Task-number: QTBUG-29012
Change-Id: I93b679f20200c149d608a1bcc65b4936a035c6a0
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index c5694d9d8c..a2e363f991 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -1000,6 +1000,14 @@ void QDockWidgetPrivate::plug(const QRect &rect)
     setWindowState(false, false, rect);
 }
 
+static void setFrameStrutEventsEnabled(const QWidget *w, bool enabled)
+{
+    if (const QWindow *window = w->windowHandle())
+        if (QPlatformWindow *platformWindow = window->handle())
+            if (platformWindow->frameStrutEventsEnabled() != enabled)
+                platformWindow->setFrameStrutEventsEnabled(enabled);
+}
+
 void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect &rect)
 {
     Q_Q(QDockWidget);
@@ -1053,9 +1061,7 @@ void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect
     }
 
     if (floating && nativeDeco)
-        if (const QWindow *window = q->windowHandle())
-            if (QPlatformWindow *platformWindow = window->handle())
-                platformWindow->setFrameStrutEventsEnabled(true);
+        setFrameStrutEventsEnabled(q, true);
 
     resizer->setActive(QWidgetResizeHandler::Resize, !unplug && floating && !nativeDeco);
 }
@@ -1391,6 +1397,8 @@ bool QDockWidget::event(QEvent *event)
         emit visibilityChanged(false);
         break;
     case QEvent::Show:
+        if (static_cast<QDockWidgetLayout *>(QDockWidget::layout())->nativeWindowDeco(isFloating()))
+            setFrameStrutEventsEnabled(this, true);
         d->toggleViewAction->setChecked(true);
         emit visibilityChanged(geometry().right() >= 0 && geometry().bottom() >= 0);
         break;