Another release of the ANTLR4 extension for VS Code was published last week. Now all ANTLR4 related information is bundled in an own sidebar, which makes it possible to avoid cluttering the vscode UI with unrelated details, if you are in other areas.
Additionally, you can now write and enable predicates in grammars. They must be written in Javascript and configured accordingly to tell the extension where it can find them. See the debugger configuration doc file for details how to set this up.