Hotfix flipped content on macOS

src/quickvnc/qvncitem.cpp

@@ -341,7 +341,16 @@ void QVncItem::grabTexture()
         auto *rhiLayer = qobject_cast<QSGRhiLayer*>(tex);
         if (rhiLayer) {
             auto *wp = QQuickWindowPrivate::get(window());
-            static bool flipped = wp->rhi->isYUpInFramebuffer();
+            static bool flipped =
+#ifdef Q_OS_MACOS
+                    // ### On mac we get isYUpInFramebuffer() = false and isYUpInNDC() = true
+                    // and the last one seems to be the correct one. But until the difference
+                    // is understood, we just hack this to true on macOS as a hotfix.
+                    true;
+            Q_UNUSED(wp);
+#else
+                    wp->rhi->isYUpInFramebuffer();
+#endif
             imgFlipped = flipped;
             newImg = rhiLayer->toImage();
         } else