STRANGE behavior on AdHoc workflow

[icm76]

I've seen the following behavior on AdHoc workflow and I don't know if this is the wanted or not:
1. user1 starts an AdHoc workflow, assignee=user2
2. user2 gets the task, he edits the task and fills in: progress=in progress + save and close (so that the task is still assigned to him)
3. later user2 returns and edits again the task fills in progress=completed + save and close (*not* task done)

-observed behavior: the task, when edited after step 3 does no longer contain the "Task done" button (maybe because it is completed) but it is not moved to "completed"
Please see the pictures:
–> https://docs.google.com/file/d/0B18EGd1d9E3PeHNXSmh0aGNINEE/edit?usp=sharing
–> https://docs.google.com/file/d/0B18EGd1d9E3PQVFuS1lab0F6N0U/edit?usp=sharing

-desired behavior: the task should be returned to user1 and be moved to "workflow - completed" in "My tasks" when the user presses "save and close" and the progress is Completed

So, is the observed bahavior correct?
Thank you,
Catalin

(alf 4.2.c)

[mitpatoliya]

this status is just for the reviewer only I mean it enables reviewer to keep track of how many tasks are in progress and completed for him.
Changing of status does not mean it should transit from one task to another.