The customization GUI initially doesn't have the 'Defaults' button enabled when recreating a world with customized settings

The bug

The customization GUI initially doesn't have the 'Defaults' button enabled when recreating a world with customized settings.

How to reproduce

1. Create new customized world with at least one changed setting on the customization GUI
2. Re-create the world and, before actually generating it, go into the customization GUI and try pressing the 'Defaults' button - it will be disabled and only be enabled once you change a setting.