I want to be able to make custom postfix completions, but I can\'t seem to find anywhere to do so and haven\'t been able to find anything online. Anyone know how?
With the latest release i.e IntelliJ IDEA 2018.1, you can. That too, without using any plugin. It's embedded into the IDE itself.
https://blog.jetbrains.com/idea/2018/02/intellij-idea-2018-1-eap-partial-git-commits-and-more/