Yes, it has been possible for a while now to download all the gmail account emails into desktop client using POP feature. But I was looking for the way to download selected messages only. Now they have it too and the name is Offline Mode. Again, exists for quite a while now, but I never tried it. Basically it allows you to download selected messages by label either taking all of them or restricting to the recent conversations only where the longest resent period is 5 years. As far as I recall about 5 years gmail accounts became widely accessible so this period covers pretty much of it.

This backup is still running so I'm yet to find how long will it take to get my "important" stuff. Anyway, after download is complete you are supposedly free to back up the underlying database (by Gears) on to any regular backup media.

Just in case I'm not the only one slow here. Don't take an offense.

Sometimes you happen to have a lot of messages in your gmail inbox, or any other "box" for this matter, and some of unread messages just happen to be buried in between, and you really need to get to these unread messages at once.
Flipping through pages is not an option (for me, lazy).

So, in "mail search" box type

is:unread label:inbox

and you'll get them all filtered and presented.

Of course, label:inbox can be replaced with any other label.