The term theme refers to a set of design elements installed in a package in a mobile device based on the Symbian platform that determines the visual appearance of the UI. Themes, also known as skins, only affect the visual appearance of the UI, the underlying architecture, interaction style, language settings, and general functionality are not affected.
Figure: Personalization through themes
The Symbian platform provides an API to allow you to support themes in your applications. Although a mobile device based on the Symbian platform can contain several themes, mobile device users can only activate one theme at a time. When a new theme is activated, the appearance of all applications that support themes is altered.
The following list contains some of the UI design elements that can change:
display background
color palette
highlights
pop-up window appearance
ring tones
common component look and feel
Themes also support SVG-T graphics, which allow them to be scalable. Themes can contain bitmaps or SVG graphics or a mixture of both.
For more information on the API that enables theme support in applications, see Skins API. For more information, see Symbian C++ API specifications.
For information on tools available for creating and modifying themes, see Nokia Developer.