这里有一个想法：

/**
 * Reactivate the sticky theme, if someone activates another theme.
 */

add_action( \'switch_theme\', \'wpse_permanent_theme\' );

function wpse_permanent_theme( $new_name )
{
    $sticky_theme_name = \'twentyfifteen\';  // Modify this to your needs!

    // Get the sticky theme info, to check if it exists (named):    
    $sticky_theme = wp_get_theme( $sticky_theme_name );

    // Reactivate the sticky theme:   
    if( $sticky_theme->get( \'Name\' ) && $sticky_theme_name !== $new_name )
    {
        remove_action( current_action(), __FUNCTION__ );
        switch_theme( $sticky_theme_name );
    }
}  

另一个要尝试的方法是删除switch_themes 功能适用于所有用户！

例如，我们可以通过以下方式即时过滤掉此功能：

/**
 *  Remove the \'switch_themes\' capability for all users.
 */

add_filter(\'user_has_cap\', function( $allcaps )
{
    if( isset( $allcaps[\'switch_themes\']  ) )
        unset( $allcaps[\'switch_themes\'] );
    return $allcaps;
});