Pop over to the Class C forum - front windows aren't very loved there, I'm afraid. Our Class C DID have the front window and it didn't leak; but sleeping near a 5' long single-pane window in cold temps is bone-chilling, to say the least. I finally solved my problem by covering the inside of the window with Reflectix insulation and then closing the curtain. Was much more comfy, temp-wise; but obliterated any view.
The only time I remember enjoying a "view" through that window was parked on the rail at Michigan Int'l Speedway on Turn #3, where the race cars were high into the turn...