What many people don't realise is that -- like in cars -- those tinted glass windows do hide what's inside in the daytime, but only as long as nobody turns the lights on inside the boat -- especially when it's not so light outside like dusk, and not at night. They also make the interior darker (and cooler), typically they transmit less than half the light through, often considerably less (15% is one standard tint). Tinted windows are really intended for privacy for VIPs in the back of cars or superyachts to stop the unwashed gazing in at them, not canal boats... 😉
The wide black frame is a styling thing, it's usually black glass bonded to the boat cabin. Shouldn't leak, probably a nightmare to repair if one gets bashed and cracked (they are glass!). I also think they look awful, but that's personal opinion, others may feel it's cool -- like big black SUVs with heavily tinted windows, as favoured by pop stars and drug dealers... 😞