Underline files with errors in project view

[TysonMN]

If a java file contains an error, then its name in the project view is underlined in red (see GrammarSource in the screenshot below). This doesn't happen for ANTLR files (see GrammarGrammar.g4 in the screenshot below).

How can I get ANTLR files containing an error to be underlined in red in the project view? Is this a setting that already exists or is this something that requires a change to the plugin?

[bjansen]

IIRC it's a feature that needs to be added to the plugin.

[TysonMN]

In that case, I think the next step is to find a link to documentation explaining how to add this feature. I looked for that before posting this issue but didn't find anything. Also helpful would be a link to the source code of a plugin that has this feature.

[bjansen]

Found it, it's pretty simple actually: https://intellij-support.jetbrains.com/hc/en-us/community/posts/360003382859-Highlight-a-file-with-errors-during-inspection