cindyb

You can buy some 'film' at Lowe's that will screen out the sun. That way it may save your fabric.

vschieve

You could use "white-out" curtain lining for the backing. Joann's has it.

NT66

I'd put the tension rod through a hanging pocket cut to fit inside the window frame, but sewed on a few inches down from the top, and make the quilt 2 or 3 inches wider on each side and have 2 or 3 inches above the hanging pocket. This way the quilt would be sure to cover the cracks......as it would actually be bigger than the window. =)