Can I tell what browser-chrome elements are visible in Firefox?

By "browser-chrome elements", I mean things like the status bar, bookmarks bar, etc. I see properties like window.statusbar.visible, but it seems to be true whether or not I show it, at least according to firebug. Am I missing something?

(Note: ultimately, I need to be able to ge开发者_Go百科t this info from a cross-site iframe for it to be useful to me, but even with a top-level script, I'm seeing this.)

window.statusbar.visible and related properties only tell you whether your popup window was opened with or without the statusbar chrome flag, and even then, that requires the dom.disable_window_open_feature.status preference to be turned off. My understanding is that the "pill" on the Mac that toggles all the toolbars also affects this flag. Other ways of hiding chrome (e.g. via View - Show/Hide - Status Bar) cannot be detected by web pages.