I quilted wavy lines from left to right as suggested in Jacquie Gering's book, Quilting Modern.
I used a purple and blue batik for the sky:
A few people asked about the size of the strips and the pattern. Here is the book that has the original pattern...mine is a couple rows narrower than the original. The quilt is about 37" square in the book and uses 1" strips. The windows are pieced into the block and are the centers of the blocks. Here is the webpage of the author, Flavin Glover. There are pictures of some of the other quilts in the book here as well and you can order the book via the webpage.
This is a picture of the original quilt in the book: