Thanks for asking that, Martin !
Suggested by Marko and @a_iulica – thanks, people ! -, these buttons allow you to finish or archive a task directly from the “view task” box.
as suggested by @mjhawkins
Thanks, Michael !
When adding a new task, the last option in the projects checkbox is now “<new project>”. Just select this option and you could add a new project on the fly.
The same is valid for lists or contexts.