Inability to Apply Custom Settings to Superflat World Type

[IlluminatiHD]

Currently it is impossible to change the world type to Superflat AND apply any custom settings.

When attempting to configure a Superflat world type with custom settings in the "customize" menu and confirming these settings by clicking "Done", the world type automatically reverts to RTG aka. Realistic Terrain Generation
The world will then generate in RTG.

Superflat worlds are still possible, although only the grass world preset will generate (and well... who likes those anyways?)

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Steps to Reproduce:

1. Select the Superflat world type.
2. Enter the "customize" menu and (optionally) change preset settings.
3. Click "Done" to confirm the settings.

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Issue is most likely related to RTG being selected once you enter the world creation menu.
This also applies to exiting sub-menus

[Yeesus]

so sad