I had the same problem, but today I discovered that right next the the regular scroll bar on the right there's a very thin grey scroll bar that appears when the mouse hovers over it..... it works and gets me to the reply button (finally), but it should be a bit more obvious.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk