Web Page plugin, when opening a _blank link, opens it in a new full screen window. JavaScript window.open event, however, opens a popup window in the same full screen space. But in both cases address bar is hidden in new window, regardless of ‘location=on’ setting in window.open.
Hiding address bar is somewhat a security issue, in modern browsers it’s, I believe, always shown, to prevent phishing. In development it’s also often needed, to copy, extract parameters, or just check where you are.