Make org-gtd-engage doesn't display subtasks of a no ready to take task.

[dev590t]

For instance,

* NEXT read book
** DONE read chap 1
** CNCL read chap 2
** NEXT read chap 3

If I decide to pause my reading of book for a moment and resume later, "read book" become a no ready to take task:

* TODO read book
** DONE read chap 1
** CNCL read chap 2
** NEXT read chap 3

did it is possible that org-gtd-engage doesn't display the task "read
chap 3"?
Why don't add that as default behavior of org-gtd-engage?