"Edit world settings" button

[NovaFlag]

This button will let the player to change some world settings after the world has been created, such as the world's name, whether or not cheats are enabled, etc (though, i don't think it should let you edit the generation preset (default, flat, structure_world), that would be really weird). When pressed it should open a menu similar to world creation menu, but instead of creating a new world it will change the setting of already existing one.

Here's an extremely-low-quality image of how it could look in the world selection menu.

[IntegratedQuantum]

This would also be useful to change the local player that is used when joining in singleplayer.

[1-fr33]

This would also be useful to change the local player that is used when joining in singleplayer.

What should be the options available inside of the edit world window, and should I move the open world folder option inside of it as well?

[IntegratedQuantum]

What should be the options available inside of the edit world window

Anything that can't (or shouldn't) be edited through a command from inside the game

defaultGamemode
allowCheats
testingMode
name
localPlayerIndex

In the future this would also include game rules and addon updating.

Anything that is (or will be) editable through a command should not be editable here.

[1-fr33]

To show the world seed, I added an option to disable the text-input field #3449

[1-fr33]

what is the localPlayerIndex, and how should a player edit it? Should the player just give a value or use a DiscreteSlider

[IntegratedQuantum]

It's the player that gets used when you join in singleplayer (it doesn't do an account lookup in that case).
Selection should be done by giving a list of player names and ids (Name@id, as shown in the player list where you can kick them in multiplayer) of all players that joined the world.