3. You need to start glue from the window and end at the door, then even if there is a small overlap somewhere, it will not be noticeable. Check the wall that is closest to the window for verticality with a plumb line, the wall is not entirely flat to draw the corresponding line — on it you will be guided by gluing wallpaper canvases. For fidelity, it is better to carry out this procedure before the sticking of each subsequent canvas.