[O] Filter agenda view to subtree

[Francesco Pizzolante]

Hi,

I would like to be able to filter the agenda view according to an Org file or
a subtree.

Currently, the only way to do that is:
1. change buffer,
2. go the desired one,
3. go to the desired subtree,
4. generate the agenda view restricted to the current subtree (C-c C-x <).

It would be good to have the ability (with a key binding) to filter directly
from the agenda view, selecting the subtree "à la refile" (having completion
for the files and subtrees). And then, be able to reset the filter to the
"full" view.

Is there a way to achieve this or does this corresponds to a new feature in
the agenda view?

Thanks for your help.

Francesco