The CM theme engine is in turn used on many other forked Android ROMs, such as Paranoid Android. Apps Firefox and Google Chrome either support or supported a form of theme. Firefox (and its sibling Thunderbird) supports themes either through lightweight themes (formerly Personas) or complete themes. While lightweight themes are simply background images for toolbar Firefox toolbars, complete themes have more power to modify Firefox's appearance. Google Chrome version 3.0 or later allows themes to alter the appearance of the browser. Internet Explorer 5 and its immediate successor allowed the background picture of their toolbars to be customized. See also Skin (computing) Computer wallpaper Look and feel User interface engineering Industrial design Aqua (user interface) References Graphical user interfaces Software add-ons