Hi Merv,
I saw this roof at a recent NSW Cobra Club picnic and will be incorporating the idea into my soft top.
The rear window zips completely out of the soft top.
It is held in at the top by a heavy zip along its entire length which is attached to the inside rear edge of the soft top.
The bottom edges are fitted under two tenax clips on each side of the roof and also under the chromed teardrops.
The benefits of this idea is that it allows fresh air to circulate throughout the cabin when the soft top is erected, even when it's raining.
Baz