How do I add a new content status? What hook would I use to add a new content status under the path admin/content?  See image below.



I am trying to give my content type(s) a new status so that I can do some more filtering on it.  Specifically, I want to create a new "draft" status.  Any pointers on where to start and API's to look at?  Or are there any existing modules that do this that I can take a look at the code?

EDIT: I would like the user filling out the form to set their own status as 'draft'.  The reason is that I am using the save_draft module (http://drupal.org/project/save_draft) that allows the user to save values in a form without submitting it.  The problem is that Drupal considers the node to be unpublished.  My editors should not see the content type if it is in "draft" mode, but since Drupal saves it as "unpublished", my editors see this and they are not sure if the content is ready to be edited or if the end user is just saving their work and finishing it up later.

The save_draft module gives me 2 buttons (Publish and Save as Draft).  This allows the user to select their own status.  I would also like this new "save as draft" status to be searchable/sortable so my editors could find out who hasn't finished submitting their unfinished draft, if need be.
You should look at the workflow module. This one is used to create additional work flows and status in your content authoring.