Themes can provide starter content in WordPress 4.7, which is displayed in the customizer of a fresh install.
Starter content for themes in 4.7
Since WordPress 4.7, themes can provide starter content to help the user set up his fresh install via the customizer. For example, a theme can bring predefined navigations and widgets for the sidebar.
Customizer improvements in 4.7
With 4.7 you don’t have to close the customizer for creating a new page before adding it to a menu. From now on, you can add a new page directly from the menu option in the customizer. This ability is also available for the
dropdown-pages option of the customizer which can be used by plugins or themes in the following way (code from the make post):
$wp_customize->add_control( 'featured_page', array( 'label' => __( 'Featured Page', 'mytextdomain' ), 'section' => 'theme_options', 'type' => 'dropdown-pages', 'allow_addition' => true, // This allows users to add new pages from this dropdown-pages control. ) );
Also, the UI of the panels was improved visually and technically. The customizer changesets keep unpublished changes in the background, so they don’t get lost on theme switch. One more new feature is a text area for custom CSS. More about that and the other changes can be found in the post »Customizer Improvements in 4.7« by Nick Halsey.