Recently, as I was building my city, I came across a problem. There's a section of my city wall that is curved, arches over a river, and I want it closed off by a sort of barred gate or barier. I'd love to use the iron portculis gates, but A) they don't look good underwater and B) they don't interconnect like fences do. That said, I'm suggesting the implementation of Gate Blocks.
Gate Blocks would take up the area of a regular 1x1 block, but they'd have the texture and opening function of the regular gates. These gate blocks would be advantagous because not only would they look good underwater, but they'd also interconnect, allowing diagonal gates instead of just flat ones.