I thought about this for a while, and it does feel better
this way. I am integrating this change.

As for the diff format, the best way to submit patches
to me for inclusion would be to make p0 or p1 unified
diffs against the latest CVS tree, with top srcdir
sourceinstall2, using diff -Naupr

But for out of tree patches restricted to a certain
component (example: sourceinstall-gtk), it is probably
ok to generate the changeset by setting the
top srcdir to the specific component directory, as
users can apply it easily to the official releases.

I think that in any case it would be better not to
include the .po changes, as those changes can make it
difficult to apply the patch to a later version with
different line numbers in the .po files.
Those files should be automatically updated during
the build process anyway.

Regarding the feature itself, I find it useful to
start browsing directories with the arrow keys
and ENTER, and this change would choose the
directory instead. But I can see your use case too.