There are Cloud IDEs that need full access to basically emulate browser tabs within their windowing system. Right now, if you’re developing a site that sends headers that doesn’t allow pages to be iframed, you can’t a preview of the site open within the page.
I understand the merit to not allowing a site to be silently iframed, as that opens up lots of potential exploits like clickjacking. However, there are some applications that look to legitimately provide a further level of chrome around the browser, in a way that a user would actually explicitly want.
I’m suggesting that there should be a function that can be called that will pop up a bar like the one for getting access to the user’s location or webcam, with a message like “http://example.com is requesting permission to open other websites.”