I finished up the cabinetry portion of the window seat project. As shown in the picture, I installed the top, which has a lift up lid. I also put a small lip on the front, which is there to keep the cushion in place.
The underside of the lid has 3/4" x 1 1/2" support splines to make sure it stays flat over time.
We need to paint the front with our white trim paint. Hopefully my DW will get the cushion made in the next couple of weeks.