Extending directory tree

i think a good feature may be a option to automatically scan the subdirectory tree (only for subdirecories) of the current directory.
in this way, with the (+) sign before the directory name could be possible to go to the any desired subdirectory without need to scan the content of each one.

or perhap i can add a custon command to do it? can i do it?

best regards,

pescadito