Well, tagging applications is probably an edge case. I *think* most
people use it just for tagging normal files. (Though maybe I'm wrong.)
You are not able to drag into the "folder" view you get when opening a
"Tag Folder"... because it is literally a search result window, not a
true folder.
Tag Folders only work when you drag items ONTO a particular Tag
Folder's icon... NOT its window... which as I said above is actually
just a Finder search window with pre-filled search criteria (i.e. a
saved search).
Why the tagging of an application doesn't work for you, I'm not sure.
I've never tried tagging a folder / app -- though maybe I will :) --
and I can't recall whether I've read anything about it or not. I so
rarely do anything with Tag Folders except drop newly created files
and search for files that I don't come read the group much.
Finally, the Spotlight comment field will not have your tags unless
you selected that option during setup. -- Are you sure you didn't
answer a dialog incorrectly for the setup you wanted? Perhaps, you
could uninstall and re-install just to be sure.
By default, tags are kept in the ... um... kItemUserTags (is that
right, guys?? doesn't sound quite right -- but it's something close to
that) metadata field. Maybe you can mdls some files to see whether
your tags are being added at all? -- Okay, I looked... it's
kOMUserTags. *knew it was something like that* (OM for OpenMeta) ...
Take a look at the output of mdls for a normal file you've tried
tagging, as well as for a folder or application. See if the tags
appear not in either case. -- If they don't appear on the files,
something is clearly wrong with your install. If they do appear for
files, but don't appear for folders / apps, maybe there's a bug /
limitation that I've just forgotten hearing about.
HTH.
-jab