Take the screen on the right here. If you're a regular, you'll recognise it as the thread page. This is where you read questions and decide whether to contribute your inputs.

And you do that by clicking on the "Reply" link. The trouble is, clicking on the link opens up a new page where only the first post (or the post you are replying to) is visible. Often, when there is a long trail of discussion, just seeing one post isn't enough - ideally, you'd like to see the messages while writing your response. So you try the next best approach - you try to open it in a new tab.
Unfortunately, doing so opens the home page of the forums (try it if you haven't so far).
That's where Gre
aSDN comes in. GreaSDN is a Greasemonkey script which adds a link to add a reply "inline". They say a picture speaks a thousand words, and here it is.There! Its added a nice little link to "Reply Inline".
OK, there's a new link. So what? What does it do?
Well, this is what it does - it allows you to write a reply - in the sa
me page.Here's the screenshot. The advantage is that you get to reply while viewing the whole history of discussions that have been going on.