I built the pergola and mounted it over the window yesterday. I am really happy with the scale and form - it definitely adds to the "cottage" look. Here are a couple of pictures of it in place...
The window is 4' wide and the pergola is 8'.
I fabricated the pergola from five 8' long pressure-treated 2x6's - total cost of about $40. After cutting, I painted each piece before assembly. In the past I have tried to paint these once assembled, which is not a easy. The rest of the shed trim will be painted this same dark brown. Once we reside the house (hoping early next year), I will mount similar structures over the windows on the west-end of the house to help filter the evening sun.
I also mounted the box-rail for the sliding door on the other gable-end. Once I build and mount the door, I will decide if I want some sort of pergola or structure over it.