Windows QPA: Add setting of dark window borders

Implement dark mode support level 1: change the
window borders to dark and back, tracking the
activation of dark mode.

Task-number: QTBUG-72028
Change-Id: I6e8b31e7ee574f4d90438405f361cd940faee7fd
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index d322b0e92b..5578259399 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -1221,6 +1221,11 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
             auto nativeInterface =
                 static_cast<QWindowsNativeInterface *>(QWindowsIntegration::instance()->nativeInterface());
             emit nativeInterface->darkModeChanged(darkMode);
+            const auto options = QWindowsIntegration::instance()->options();
+            if ((options & QWindowsIntegration::DarkModeWindowFrames) != 0) {
+                for (QWindowsWindow *w : d->m_windows)
+                    w->setDarkBorder(QWindowsContextPrivate::m_darkMode);
+            }
         }
         return d->m_screenManager.handleScreenChanges();
     }