unreal slate 创建 window

	testWindow = SNew(SWindow)
		.Title(LOCTEXT("Asset Window", "Asset Window"))
		.ClientSize(FVector2D(30, 20))
		.SupportsMaximize(false)
		.SupportsMinimize(false)
		.SizingRule(ESizingRule::Autosized)
		.AutoCenter(EAutoCenter::None)
		.IsInitiallyMaximized(false)
		.bDragAnywhere(true)
		[
			textBlock.ToSharedRef()
		];

	TSharedPtr<SWindow> TopWindow = FSlateApplication::Get().GetActiveTopLevelWindow();
	if (TopWindow.IsValid())
	{
		//Add as Native
		FSlateApplication::Get().AddWindowAsNativeChild(testWindow.ToSharedRef(), TopWindow.ToSharedRef(), true);
	}
	else
	{

		//Default in case no top window
		FSlateApplication::Get().AddWindow(testWindow.ToSharedRef());
	}

	GEngine->GameViewport->AddViewportWidgetContent(SNew(SWeakWidget).PossiblyNullContent(testWindow.ToSharedRef()));