I'd like to know how to create a creative dimension while all the other worlds are in survival.
The question can be splitted into two:

• How to toggle creative mode when going through the portal in one or another direction?
• How to save the survival inventory to restore it when the player comes back? (To prevent cheating)

With more investigation I noticed the fe.protection.gamemode value which can be used to toggle a gamemode in an area. However, it works pretty fine on an area inside a world but doesn't seem to work on a whole dimension:

• I am in survival, I go to the dimension --> Creative // OK
• I am go back to the original dimension --> Creative // Not OK

It only does so like this. If I am in creative before going, I am still in creative when I come back. Quite strange.

You need to do 2 things:

• assign a command on enter and exist of the zone the dimension is that puts the player into creative when entering and back to survival when leaving.
• set a value for fe.protection.inventorygroup for that zone.

However, the latter might or not function correctly. See #2228

Duplicate of #2228