+1
yeah, it's come up before, and I'd like the idea to be able to do that, but some sort of trickery will be needed in order to do this since the 'reply' button will probably be a right click menu option on either search results, or collections, which aren't as clear-cut as headers... which is why rdl hasn't put this feature in I suppose.
Since my last format I havent even bothered to install a header capable reader since I very rarely used it (ie, for the reply thing and for the rare header surfing..), and I'd rather not install one either.