Since when could you click on the column headers in black...

[tuvor]

...to sort the original posts?

[Mojambo]

1. Whoa.

I didn't know you could do that.

[EC]

2. Always I think

my eyesight isn't so hot without my glasses and I miss the links alot and end up hitting the top line and find myself in the forum instead of the post.

[MrScorpio]

3. Since always

I've done it a few times in the past

[Bossy Monkey]

4. Since July 6, 2003

It's a feature of DU2. Old original DU looked similar, but not quite the same: http://www.democraticunderground.com/cgi-bin/duforum/duboard.cgi?az=lobby
To see actual threads, you have to click on one of the fora, then click Archive.
The switchover to DU2 was quite the thing. For a couple of weeks we could rate threads. Unfortunately it was too much of a strain on the servers so the feature was discontinued, but it was pretty cool.

[DrDebug]

5. If you click on Expand threads then you can also sort on views

Which give a very strange order. You would think that the posts with most replies also have the most views, but that's not the case...

[Bossy Monkey]

6. "Views" was another feature of DU2 that went away after a couple weeks

I think the Sort by Views feature is probably not actually reflective of actual views, since there was a thread that had been locked immediately which nevertheless was on the front page. For all that people might have been curious and might have wanted to see what would have gotten it locked, still it was locked immediately and would have fallen off the front page very quickly. Don't see how it could have been on the top of the heap as far as Views go. Probably Sort by Views actually sorts by some other criterion (or it sorts fewest to most views).

[Worst Username Ever]

7. Always?