Wallpaper Around Windows Video
How do you get the wallpaper to match perfect above and below the window? You can't just draw a plumb line and hang the wallpaper. If you do the wallpaper pattern might not match the wallpaper that is already hung.
Most wallpaper, pre-pasted styles, expand when the activator is applied. In some cases, as much as 3/8" of an inch. Mark the wall with a plumb line that is 1/8" longer then the width of the wallpaper after the activator has been applied. Then when hanging the paper, keep it an 1/8" away from the line. That will ensure the seams top and bottom will look perfect.