How to force update a hidden window?

Thanks for the answer. I destroy the hiddenNode in the destructor of the RenderWidgetHostViewQtDelegateQuick. The problem is that QtWebEngine sends the “loaded” signal, which means that a page been loaded. But when I show the window with webview, it appears with white background for a second or two. It’s looks terribly. As I understand, the problem connected to the way of update QSG