From a882ffc603bdc663e3d32905a1817a45167b84b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Tue, 31 Jul 2018 17:32:25 +0200
Subject: [PATCH] Handle screen changes for non-top-level windows
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The platform may emit screen changes for child windows before top-level
windows, so we need to update the top level screen as soon as possible.

Change-Id: I090c620725c9c3171f5b038708d78ddfeec8512d
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
---
 src/gui/kernel/qguiapplication.cpp | 6 +++---
 src/gui/kernel/qwindow.cpp         | 4 ++--
 src/gui/kernel/qwindow_p.h         | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 91348265cd..712699ddc9 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -2338,11 +2338,11 @@ void QGuiApplicationPrivate::processWindowScreenChangedEvent(QWindowSystemInterf
     if (QWindow *window  = wse->window.data()) {
         if (window->screen() == wse->screen.data())
             return;
-        if (window->isTopLevel()) {
+        if (QWindow *topLevelWindow = window->d_func()->topLevelWindow(QWindow::ExcludeTransients)) {
             if (QScreen *screen = wse->screen.data())
-                window->d_func()->setTopLevelScreen(screen, false /* recreate */);
+                topLevelWindow->d_func()->setTopLevelScreen(screen, false /* recreate */);
             else // Fall back to default behavior, and try to find some appropriate screen
-                window->setScreen(0);
+                topLevelWindow->setScreen(0);
         }
         // we may have changed scaling, so trigger resize event if needed
         if (window->handle()) {
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 75f63c046f..3d7d22959d 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -2605,14 +2605,14 @@ void QWindowPrivate::maybeQuitOnLastWindowClosed()
     }
 }
 
-QWindow *QWindowPrivate::topLevelWindow() const
+QWindow *QWindowPrivate::topLevelWindow(QWindow::AncestorMode mode) const
 {
     Q_Q(const QWindow);
 
     QWindow *window = const_cast<QWindow *>(q);
 
     while (window) {
-        QWindow *parent = window->parent(QWindow::IncludeTransients);
+        QWindow *parent = window->parent(mode);
         if (!parent)
             break;
 
diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index 745ff2e46f..bf5e645114 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -125,7 +125,7 @@ public:
 
     QPoint globalPosition() const;
 
-    QWindow *topLevelWindow() const;
+    QWindow *topLevelWindow(QWindow::AncestorMode mode = QWindow::IncludeTransients) const;
 
 #if QT_CONFIG(opengl)
     virtual QOpenGLContext *shareContext() const;