private void PresentationSourceChangedHandler(object sender, SourceChangedEventArgs args) { if (args.NewSource != null) { var newSource = (HwndSource)args.NewSource; source = newSource; if (source != null) { var notifyDpiChanged = !matrix.Equals(source.CompositionTarget.TransformToDevice); matrix = source.CompositionTarget.TransformToDevice; sourceHook = SourceHook; source.AddHook(sourceHook); if (notifyDpiChanged) { managedCefBrowserAdapter.NotifyScreenInfoChanged(); } } } else if (args.OldSource != null) { RemoveSourceHook(); } }