1 files changed, 15 insertions, 1 deletions
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 159e1250d0..d639f27c1a 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -1077,6 +1077,7 @@ QWindowCreationContext::QWindowCreationContext(const QWindow *w,
 */
 
 const char *QWindowsWindow::embeddedNativeParentHandleProperty = "_q_embedded_native_parent_handle";
+const char *QWindowsWindow::hasBorderInFullScreenProperty = "_q_has_border_in_fullscreen";
 
 QWindowsWindow::QWindowsWindow(QWindow *aWindow, const QWindowsWindowData &data) :
     QWindowsBaseWindow(aWindow),
@@ -1115,6 +1116,8 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const QWindowsWindowData &data)
 
     if (aWindow->isTopLevel())
         setWindowIcon(aWindow->icon());
+    if (aWindow->property(hasBorderInFullScreenProperty).toBool())
+        setFlag(HasBorderInFullScreen);
     clearFlag(WithinCreate);
 }
 
@@ -2662,15 +2665,26 @@ void QWindowsWindow::setHasBorderInFullScreenStatic(QWindow *window, bool border
     if (QPlatformWindow *handle = window->handle())
         static_cast<QWindowsWindow *>(handle)->setHasBorderInFullScreen(border);
     else
-        qWarning("%s invoked without window handle; call has no effect.", Q_FUNC_INFO);
+        window->setProperty(hasBorderInFullScreenProperty, QVariant(border));
 }
 
 void QWindowsWindow::setHasBorderInFullScreen(bool border)
 {
+    if (testFlag(HasBorderInFullScreen) == border)
+        return;
     if (border)
         setFlag(HasBorderInFullScreen);
     else
         clearFlag(HasBorderInFullScreen);
+    // Directly apply the flag in case we are fullscreen.
+    if (m_windowState == Qt::WindowFullScreen) {
+        LONG_PTR style = GetWindowLongPtr(handle(), GWL_STYLE);
+        if (border)
+            style |= WS_BORDER;
+        else
+            style &= ~WS_BORDER;
+        SetWindowLongPtr(handle(), GWL_STYLE, style);
+    }
 }
 
 QString QWindowsWindow::formatWindowTitle(const QString &title)