Sets the sub-theme for a button-toggle in a control-bar control.

Sub-themes allow you to tweak the styling on control types within a component without having to change the main theme of the component. This approach is often preferable to manually changing the styling on individual controls by changing individual style settings. If you leave this property blank the default ('base') sub-theme is used.

A sub-theme is a variation on the main theme or 'style' of a component. This main style is defined using the Style name property in the UX Properties section. Once a style for the component is selected, this will determine the available sub-themes for a given control type. You can create your own sub-themes. For information on how to do this visit the 'Local sub-theme definitions - Javascript' property page in the UX Properties section.