3 files changed, 31 insertions, 13 deletions

diff --git a/src/gui/kernel/qevent.h b/src/gui/kernel/qevent.h
index fb72c561ab..93374b2299 100644
--- a/src/gui/kernel/qevent.h
+++ b/src/gui/kernel/qevent.h
@@ -537,8 +537,8 @@ public:
     };
     class Attribute {
     public:
-        Attribute(AttributeType t, int s, int l, QVariant val) : type(t), start(s), length(l), value(qMove(val)) {}
-        Attribute(AttributeType t, int s, int l) : type(t), start(s), length(l), value() {}
+        Attribute(AttributeType typ, int s, int l, QVariant val) : type(typ), start(s), length(l), value(qMove(val)) {}
+        Attribute(AttributeType typ, int s, int l) : type(typ), start(s), length(l), value() {}
 
         AttributeType type;
         int start;
diff --git a/src/gui/kernel/qplatformwindow.cpp b/src/gui/kernel/qplatformwindow.cpp
index e45a1d61ba..bcd3e830dd 100644
--- a/src/gui/kernel/qplatformwindow.cpp
+++ b/src/gui/kernel/qplatformwindow.cpp
@@ -581,6 +581,20 @@ void QPlatformWindow::invalidateSurface()
 {
 }
 
+static QSize fixInitialSize(QSize size, const QWindow *w,
+                            int defaultWidth, int defaultHeight)
+{
+    if (size.width() == 0) {
+        const int minWidth = w->minimumWidth();
+        size.setWidth(minWidth > 0 ? minWidth : defaultWidth);
+    }
+    if (size.height() == 0) {
+        const int minHeight = w->minimumHeight();
+        size.setHeight(minHeight > 0 ? minHeight : defaultHeight);
+    }
+    return size;
+}
+
 /*!
     Helper function to get initial geometry on windowing systems which do not
     do smart positioning and also do not provide a means of centering a
@@ -593,19 +607,18 @@ void QPlatformWindow::invalidateSurface()
 QRect QPlatformWindow::initialGeometry(const QWindow *w,
     const QRect &initialGeometry, int defaultWidth, int defaultHeight)
 {
+    if (!w->isTopLevel()) {
+        const qreal factor = QHighDpiScaling::factor(w);
+        const QSize size = fixInitialSize(QHighDpi::fromNative(initialGeometry.size(), factor),
+                                          w, defaultWidth, defaultHeight);
+        return QRect(initialGeometry.topLeft(), QHighDpi::toNative(size, factor));
+    }
     const QScreen *screen = effectiveScreen(w);
     if (!screen)
         return initialGeometry;
     QRect rect(QHighDpi::fromNativePixels(initialGeometry, w));
-    if (rect.width() == 0) {
-        const int minWidth = w->minimumWidth();
-        rect.setWidth(minWidth > 0 ? minWidth : defaultWidth);
-    }
-    if (rect.height() == 0) {
-        const int minHeight = w->minimumHeight();
-        rect.setHeight(minHeight > 0 ? minHeight : defaultHeight);
-    }
-    if (w->isTopLevel() && qt_window_private(const_cast<QWindow*>(w))->positionAutomatic
+    rect.setSize(fixInitialSize(rect.size(), w, defaultWidth, defaultHeight));
+    if (qt_window_private(const_cast<QWindow*>(w))->positionAutomatic
             && w->type() != Qt::Popup) {
         const QRect availableGeometry = screen->availableGeometry();
         // Center unless the geometry ( + unknown window frame) is too large for the screen).
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index fa26fd77a3..f061a2bf50 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -402,7 +402,7 @@ void QWindowPrivate::create(bool recursive)
         q->parent()->create();
 
     platformWindow = QGuiApplicationPrivate::platformIntegration()->createPlatformWindow(q);
-    Q_ASSERT(platformWindow);
+    Q_ASSERT(platformWindow || q->type() == Qt::ForeignWindow);
 
     if (!platformWindow) {
         qWarning() << "Failed to create platform window for" << q << "with flags" << q->flags();
@@ -2432,7 +2432,8 @@ QWindow *QWindowPrivate::topLevelWindow() const
     This can be used, on platforms which support it, to embed a QWindow inside a
     native window, or to embed a native window inside a QWindow.
 
-    If foreign windows are not supported, this function returns 0.
+    If foreign windows are not supported or embedding the native window
+    failed in the platform plugin, this function returns 0.
 
     \note The resulting QWindow should not be used to manipulate the underlying
     native window (besides re-parenting), or to observe state changes of the
@@ -2453,6 +2454,10 @@ QWindow *QWindow::fromWinId(WId id)
     window->setFlags(Qt::ForeignWindow);
     window->setProperty("_q_foreignWinId", QVariant::fromValue(id));
     window->create();
+    if (!window->handle()) {
+        delete window;
+        return nullptr;
+    }
     return window;
 }