If a site attempts to load an activex control, the modern IE will prompt you that the site must be opened in desktop mode to view the site's full contents properly (along with a button to do so) at the bottom of the screen above the address bar. Site developers can also add a meta tag to their site that will force this prompt in IE10 as well, if necessary, to avoid this.
However, modern IE doesn't actually allow loading of any activex controls (except Flash, which is technically baked into the browser now ala Google Chrome), so there's no bar specifically for those.