<a href="http://imgur.com/4Jk3S58" rel="nofollow">http://imgur.com/4Jk3S58</a>
In that image the rogue should be able to throw a dagger at the fighter. It has always been in 3.5 and Pathfinder that if the rogue was in that position they would both have line of sight to each other, and the rogue would have cover from the fighter, but the fighter would have no cover. Well in Roll20 in those positons the rogue would not even see the fighter at all. It would look like this: <a href="http://imgur.com/4dywkLV" rel="nofollow">http://imgur.com/4dywkLV</a>