If you're talking about actual new windows that are a separate process, those have been blocked by popup blockers for years. As far as popovers that block the

If you're talking about actual new windows that are a separate process, those have been blocked by popup blockers for years. As far as popovers that block the screen/annoy you, those are just HTML elements that are positioned on top of normal content - its not a "special" thing backed into the DOM API. There's really no effective way to stop a page from being able to do that unless you disable javascript entirely.