I was trying to build a facility on land that was filled with water on the inside, using glass panes to see into it. However, when I tried to place water sources on the inside of the glass panes, I then went outside of the facility and saw these water source blocks had come straight through the glass and were pouring out onto the outside. That can't be right.

I then tested it making a 3x3 square of glass panes on the floor, and sure enough whenever I placed water on a glass pane block, water flowed straight through the glass, as well as water being on the inside too, which looked rather hideous. When I put water into the central block in the 3x3 square, the water stayed in its one block and didn't even flow to the glass panes, leading to a block of water surrounded by awkward half-block air pockets.

I mean, this makes sense for iron bars and fences, but not glass panes.