Support for Māori macron characters
Add the mim file to ~/.m17n.d and restart the iBus daemon (or log in and out).
You should now be able to select English => Māori as your language input.
Using macrons now can be done by using backtick plus the letter you want to write., e.g. `a for ā
The reason for not using the right Alt or AltGr key, is that these combinations are already bound to other special characters.