We had a leak in the same area and our dealer spent significant time tracking it down. They resealed almost everything on the roof, replaced both A/C gaskets, pulled the awning off, replaced running lights, removed and reset the window and probably more that I don't remember. The problem was found to be missing screws on the rear of the coach holding the gutter on. With the screws gone, there was a hole that led right into the inside of the aluminum top sill for the wall. Water rand through that, all the way to above the window in the front and dumped there.
Moral of the story? Start in a small radius from the problem and keep working your way out. The issue could be on the opposite side of the coach!