From 045a143c2c72c72f264dd40f5da2994e647dc0ee Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Tue, 11 Feb 2020 09:44:35 +0100
Subject: [PATCH] Fix RollEffect misplacements in High DPI setups
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Pass the correct screen as parent of the roll effect widget.

Fixes: QTBUG-82011
Change-Id: I25c163cb2e4c038e60ceced702a1ea6c18aa5424
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>
---
 src/widgets/widgets/qeffects.cpp | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/widgets/widgets/qeffects.cpp b/src/widgets/widgets/qeffects.cpp
index 7069ef0368..fe1bdac644 100644
--- a/src/widgets/widgets/qeffects.cpp
+++ b/src/widgets/widgets/qeffects.cpp
@@ -54,6 +54,15 @@
 
 QT_BEGIN_NAMESPACE
 
+static QWidget *effectParent(const QWidget* w)
+{
+    const int screenNumber = w ? QGuiApplication::screens().indexOf(w->screen()) : 0;
+    QT_WARNING_PUSH // ### Qt 6: Find a replacement for QDesktopWidget::screen()
+    QT_WARNING_DISABLE_DEPRECATED
+    return QApplication::desktop()->screen(screenNumber);
+    QT_WARNING_POP
+}
+
 /*
   Internal class QAlphaWidget.
 
@@ -98,12 +107,9 @@ static QAlphaWidget* q_blend = 0;
 /*
   Constructs a QAlphaWidget.
 */
-QT_WARNING_PUSH
-QT_WARNING_DISABLE_DEPRECATED // ### Qt 6: Find a replacement for QDesktopWidget::screen()
 QAlphaWidget::QAlphaWidget(QWidget* w, Qt::WindowFlags f)
-    : QWidget(QApplication::desktop()->screen(QDesktopWidgetPrivate::screenNumber(w)), f)
+    : QWidget(effectParent(w), f)
 {
-QT_WARNING_POP
 #ifndef Q_OS_WIN
     setEnabled(false);
 #endif
@@ -383,7 +389,7 @@ static QRollEffect* q_roll = 0;
   Construct a QRollEffect widget.
 */
 QRollEffect::QRollEffect(QWidget* w, Qt::WindowFlags f, DirFlags orient)
-    : QWidget(0, f), orientation(orient)
+    : QWidget(effectParent(w), f), orientation(orient)
 {
 #ifndef Q_OS_WIN
     setEnabled(false);