Hi. UPVC windows have gone in on our new build today. Just been for a nosey on site and found something odd. Wondered if anyone could explain it or confirm my suspicions please On the window in the snap attached, both left and right opens and closes tight on the handle, no issues. The centre unit also opens, hinged from the top. Wasn't expecting this. There's no handle or anything whatsoever to secure it closed - It just lifts open from the bottom. A further nose at the same type of window at one of the neighbouring houses - The centre window doesn't open, but pushing it I could see a small gap between the bottom of the rubber seal and the UPVC frame. I opened the windows either side of the centre one and could see in the channels that a brass screw has been crudely screwed into the frame and centre units - That's all that's holding the centre unit closed. Is there something else that will happen with these windows to properly secure them, or is as it appears to my layman's eye? ..That the centre units aren't supposed to open and they've been manufactured to the wrong spec? Thanks in advance.