Implement equivalent to the wizard API

Migrate 2.6 on D7 introduced a "Wizard API" - a base class providing housekeeping to aid in developing step-by-step wizards for configuring a migration from a particular type of source (Drupal, WordPress, etc.). An implementing module (e.g., migrate_d2d, wordpress_migrate) registers its wizard class, which adds an "Import from Drupal" (or whatever) subtab to the migration dashboard. What I'd like to see going forward is an Add Group (or simple +) button on the dashboard, which leads to a selection of which migration tool to use to define a migration group - the Drupal tool, the WordPress tool, etc. The configuration screen(s) provided by the specific module should be usable not only for initial configuration (as they are now), but to edit the configuration after the group has been created. Much more thought needed here on the details...