Well spotted. There should be a seal that sits in a sill, fitted to the windscreen frame. The door opens with the quarter-light being attached to it. You can see on top of the door is a nickeled bar - inside this is a runner for the glass. The car has novel wind-up windows which work by using a slim chain inside the door. You raise the bar, turn the window handle, it turns only one way for the glass to rise then fall within this runner and the opposite runner inside the quarter-light frame. If it starts raining the driver can pull up the soft-top with one hand then wind up the windows and, hey-presto, the driver and passenger are enclosed inside, out from the rain, in about ten seconds (or so).