Task dependencies

I know that Kent Beck says that we should not need to record task dependencies in our Agile Scheduling.

But, for my personal tasks, it would be nice to have task dependencies taken into account.

E.g. perhaps hiding or graying out tasks that cannot be done yet because of other tasks they depend on.

(In many ways, a task dependency is like a "start by" date.    As in "this task cannot be started until such and such a date.  Whereas other tasks can be dome at any time, but you just give them a "tickle date" to remind you to pay attention.  I may want to hide the former, although I think that I opreger graying.)

As in, propagating due dates: if Task B depends on Task A, and B has a due date Tb, then  A must be done by that date - and possibly earlier, e.g. if you provide a work estimate.   (Hmm, work estimates could be "number of days", "number of weekend days", etc.)