Better superflat customisation GUI for Java

Currently, the superflat customization is a bit inaccessible for newer players. Presets are a good way the game has handled that problem, but for further customization, you need to type in the code for the generation. What I suggest is to make the "layers" page on the superflat world creation screen interactive so that you can change the blocks making up the layer, biome, structures, layer thickness etc. This would make superflat world customization more easily understandable for new players.