The gigantic screen windows have flaps on both the inside and outside, and the whole tent is constructed of canvas in bright colors. The top is deep blue, while the sides are yellow and the front flap has red, yellow, and blue stripes. The reinforced beaded edge of this flap normally slides into a metal strip on the bus to effect a weathertight seal. Here the flap has been pushed back over the tent to get it out of the way. You can easily see the zippered door that closes when the bus is away from the campsite, as well as the connecting flap shown above.
Interior shot shows how the zippered door can be rolled up and tied off when the bus is docked.
One may be a kludge, or they're probably year variations.