Didn't see that until after Mike closed it, so I'll put it here. There is a way to view the entire thread without using Preview Post. Below the dialog box the last few posts are displayed, at the end of the list is a link to view the entire thread that opens in a new window. Click that and you can see if anything new has been posted. Saves you from doing Preview Post every time as it's in a new window and you can just hit Refresh.