* How should async rendering interact with throttling the painting of a hidden plugin? With the current spec, NPP_DidComposite may not fire on hidden plugins, so when you make a hidden plugin visible the browser will render a frame with arbitrarily old plugin contents and then fire DidComposite. There could be flicker as the plugin updates. Fundamentally, the need to re-render a previously hidden plugin conflicts with the goal that the browser not block on plugin rendering.