Their is a bar that goes between them and over the cage it also stops the rain pooling on the roof you can see the line of it under the roof in the photo.
Here are a few closer shots of the for parts while it's off for summer.
Top bar that goes from the top of each door and over the roll cage.
Top rail of the door frame with hole for the top bar which is an original hole.
You can see here how I folded the edges over after cutting
Just above the small side windows you can see a strip of velcro along with a couple of press studs to seal this edge
You can see at the top just above the V shaped window the full length velcro strip to join the two part together along with the straps at the top which velcro around the cage across the top too