Recommended tool to edit java.g ?

[mickaelistria]

Hi all,
I'm trying to have fun with the java.g file to add capabilities to the parser (my current experiment, which is not likely to be successful anytime soon, is to add some support for unnamed classes/JEP 445). I've started to use https://github.com/MaisiKoleni/gedit which does a decent job; but I'm wondering whether there are some alternative or additional tools recommended to edit the grammar efficiently?
Thanks in advance