In an application, themes can come from the following sources:
The first two theme sources are available at design time via the C1ThemeController properties and designer actions. At runtime, you can also load themes in code from .c1theme files on disk using methods available on the C1ThemeController component.
The built-in themes can be applied through code using the RegisterTheme and SetTheme methods and ApplicationTheme property of the C1ThemeController class. With the RegisterTheme method, the user can load a built-in theme from a file and register it for use by theme controllers in the application. The SetTheme method can be used to set control-wise themes, while the Application Theme property can set an application-wide theme, so that all the controls in an application that have "(default)" as their Theme property will use the same theme.