Keep toplevel windows in the top left corner of the screen

We can't know the actual position of a window on the screen. This causes
an issue when Widgets try to position a popup/menu absolutely and keep
it on the screen when the screen geometry doesn't include (0,0).
Instead report their positions always as the top left corner of
the screen that they are on.
This new behavior can be disabled for qt-shell or via an environment
variable by users that rely on the old behavior.

Fixes: QTBUG-85297
Change-Id: Iacb91cb03a0df87af950115760d2f41124ac06a3
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Edmundson <davidedmundson@kde.org>
Reviewed-by: Aleix Pol Gonzalez <aleixpol@kde.org>
(cherry picked from commit a46795a22e05722917c6ebc60ed01bebf49898ae)
Reviewed-by: Ilya Fedin <fedin-ilja2010@ya.ru>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

4 files changed, 20 insertions, 1 deletions

diff --git a/src/client/qwaylandintegration.cpp b/src/client/qwaylandintegration.cpp
index ed04e403..6d74de13 100644
--- a/src/client/qwaylandintegration.cpp
+++ b/src/client/qwaylandintegration.cpp
@@ -86,6 +86,9 @@ QWaylandIntegration::QWaylandIntegration()
         return;
     }
 
+    QWaylandWindow::fixedToplevelPositions =
+            !qEnvironmentVariableIsSet("QT_WAYLAND_DISABLE_FIXED_POSITIONS");
+
     // ### Not ideal...
     // We don't want to use QPlatformWindow::requestActivate here, since that gives a warning
     // for most shells. Also, we don't want to put this into the specific shells that can use
diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index e8b50939..d669e839 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -331,8 +331,13 @@ void QWaylandWindow::setGeometry_helper(const QRect &rect)
     }
 }
 
-void QWaylandWindow::setGeometry(const QRect &rect)
+void QWaylandWindow::setGeometry(const QRect &r)
 {
+    auto rect = r;
+    if (fixedToplevelPositions && !QPlatformWindow::parent() && window()->type() != Qt::Popup
+        && window()->type() != Qt::ToolTip) {
+        rect.moveTo(screen()->geometry().topLeft());
+    }
     setGeometry_helper(rect);
 
     if (window()->isVisible() && rect.isValid()) {
@@ -1226,6 +1231,13 @@ void QWaylandWindow::handleScreensChanged()
 
     QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->QPlatformScreen::screen());
     mLastReportedScreen = newScreen;
+    if (fixedToplevelPositions && !QPlatformWindow::parent() && window()->type() != Qt::Popup
+        && window()->type() != Qt::ToolTip
+        && geometry().topLeft() != newScreen->geometry().topLeft()) {
+        auto geometry = this->geometry();
+        geometry.moveTo(newScreen->geometry().topLeft());
+        setGeometry(geometry);
+    }
 
     int scale = newScreen->isPlaceholder() ? 1 : static_cast<QWaylandScreen *>(newScreen)->scale();
     if (scale != mScale) {
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index e1280268..d2d4d659 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -76,6 +76,9 @@ public:
     QWaylandWindow(QWindow *window, QWaylandDisplay *display);
     ~QWaylandWindow() override;
 
+    // Keep Toplevels position on the top left corner of their screen
+    static inline bool fixedToplevelPositions = true;
+
     virtual WindowType windowType() const = 0;
     virtual void ensureSize();
     WId winId() const override;
diff --git a/src/plugins/shellintegration/qt-shell/qwaylandqtshellintegration.cpp b/src/plugins/shellintegration/qt-shell/qwaylandqtshellintegration.cpp
index 9b7b38b4..17b87033 100644
--- a/src/plugins/shellintegration/qt-shell/qwaylandqtshellintegration.cpp
+++ b/src/plugins/shellintegration/qt-shell/qwaylandqtshellintegration.cpp
@@ -22,6 +22,7 @@ namespace QtWaylandClient {
 QWaylandQtShellIntegration::QWaylandQtShellIntegration()
     : QWaylandShellIntegrationTemplate(1)
 {
+    QWaylandWindow::fixedToplevelPositions = false;
 }
 
 QWaylandShellSurface *QWaylandQtShellIntegration::createShellSurface(QWaylandWindow *window)