The panel is not attached to anything. It is just supported by beveled cut sticks along the sides and the metal over the windshield. The edges of the plywood sit on top of the supporting sticks. The plywood is bowed so it will not sag.
The bow will change a little because the panel will expand and shrink as the temperature and humidity change.
The plywood is a little below the 2X4 in the center. The 2X4 will restrict how far the roof will raise if some pushes up on the center. I was concerned if the plywood raised too far it might come off the side supports.
Go thru the slides in the first link again. I have pictures and comments showing the process.
