From 60bdf6a5c63572caff371dc3c285679bdbca472a Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Tue, 4 May 2021 14:35:39 +0200
Subject: QMdiArea: Fix top level window title when using
 DontMaximizeSubWindowOnActivation

When trying to find the original window title, check for another
maximized sub window and use its title. Protect the calls to
setWindowTitle to prevent the original title from being cleared.

Fixes: QTBUG-92240
Change-Id: I55175382ab261b4cf8b5528304adaaec4fbe2c31
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
(cherry picked from commit 8886462872db9cdab4d7683823fd24fb9f8920c4)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/widgets/widgets/qmdisubwindow.cpp | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

(limited to 'src/widgets/widgets/qmdisubwindow.cpp')

diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index 89f2df5524..27b89ee212 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -259,11 +259,28 @@ static inline ControlElement<T> *ptr(QWidget *widget)
     return nullptr;
 }
 
+QString QMdiSubWindowPrivate::originalWindowTitleHelper() const
+{
+    Q_Q(const QMdiSubWindow);
+    // QTBUG-92240: When DontMaximizeSubWindowOnActivation is set and
+    // there is another subwindow maximized, use its original title.
+    if (auto *mdiArea = q->mdiArea()) {
+        const auto &subWindows = mdiArea->subWindowList();
+        for (auto *subWindow : subWindows) {
+            if (subWindow != q && subWindow->isMaximized()) {
+                auto *subWindowD = static_cast<QMdiSubWindowPrivate *>(qt_widget_private(subWindow));
+                if (!subWindowD->originalTitle.isNull())
+                    return subWindowD->originalTitle;
+            }
+        }
+    }
+    return q->window()->windowTitle();
+}
+
 QString QMdiSubWindowPrivate::originalWindowTitle()
 {
-    Q_Q(QMdiSubWindow);
     if (originalTitle.isNull()) {
-        originalTitle = q->window()->windowTitle();
+        originalTitle = originalWindowTitleHelper();
         if (originalTitle.isNull())
             originalTitle = QLatin1String("");
     }
@@ -278,11 +295,17 @@ void QMdiSubWindowPrivate::setNewWindowTitle()
         return;
     QString original = originalWindowTitle();
     if (!original.isEmpty()) {
-        if (!original.contains(QMdiSubWindow::tr("- [%1]").arg(childTitle)))
-            q->window()->setWindowTitle(QMdiSubWindow::tr("%1 - [%2]").arg(original, childTitle));
+        if (!original.contains(QMdiSubWindow::tr("- [%1]").arg(childTitle))) {
+            auto title = QMdiSubWindow::tr("%1 - [%2]").arg(original, childTitle);
+            ignoreWindowTitleChange = true;
+            q->window()->setWindowTitle(title);
+            ignoreWindowTitleChange = false;
+        }
 
     } else {
+        ignoreWindowTitleChange = true;
         q->window()->setWindowTitle(childTitle);
+        ignoreWindowTitleChange = false;
     }
 }
 
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