Styles, design tokens and components follow the default theme

Problem/Motivation

The Styles and Design tokens panels offer the definitions of every installed theme, the admin theme included, while the Canvas renders on the front theme. The component Library lists the components of every installed theme too. Only its Exclude providers setting hides one, and a newly installed theme shows up in every profile.

Proposed resolution

Give the default theme to the Styles form, with #drupal_theme, and to the Design tokens form, with getDefinitionsForTheme(). Its base themes and the modules come with it, as ui_styles and ui_skins already do. In the Library, list the components of the default theme, its base themes and modules. A new Include other themes setting adds an installed theme. Exclude providers stays for modules and themes, and wins over the include.

Remaining tasks

• Library setting, schema and kernel test.
• Change record.
• Review.

User interface changes

Styles and tokens come from the default theme, its base themes and modules. The component Library settings get Include other themes. An existing profile stops listing the components of other themes until one is included.

API changes

None.

Data model changes

New include_themes list in the component Library island settings, empty by default.