Using Themes

A theme is a combination of CSS and skins used to give an application a complete, coherent look. The default theme in Flex 4 is Spark. In Flex 3, the default theme was Halo, but even Flex 3 (i.e., MX namespace) components in Flex 4 now use the Spark theme for consistency.

Although a theme can consist of just a CSS file, a theme is normally created in a SWC format, which will wrap together the CSS code plus all of the assets required, like the images, fonts, and MXML skin files. You can create your own themes, using the CSS and skinning information already presented, download free ones available online, or purchase commercial themes. The Flex SDK and Flash Builder both ship with a few themes, too.