I asked about this on Reddit, and McJty responded, but I figured I'd post it here, mainly as a reminder, but also so it will be listed with the other issues.

If you create a dimension and do not define any effects, there is a chance you will get some effects while in the dimension (blindness, etc.) This is, of course, supposed to happen--if you want to make sure it doesn't, you can use an Effect None dimlet when creating the dimension.

However, if you do not use said dimlet, and the dimension does generate with effects, trying to add an Effect None dimlet using the Dimension Editor doesn't get rid of the effects. Looking at a saved dump of the dimension information created using /rftdim savedim, it appears that it adds effect 0 (i.e. no effect) to the list of effects for the dimension, but it doesn't remove effects that are already there.

To reproduce:

1. Create dimensions, without specifying any Effect dimlets, until you find one that gives you some type of effect.
2. Add an Effect None dimlet to that dimension using a Dimension Editor.
3. Return to the dimension, and find that the effects still exist.

Workaround:
After adding an Effect None dimlet to a dimension using a dimension editor, you can use the /rftdim effectlist and /rftdim effectdel commands to remove all effects from the dimension manually, or have an op do so if you don't have the correct permissions.

Thanks for making this a ticket

No problem.

Fixed in next version (3.12)