Hi @Sören_Geier - that’s correct, you’ll need to use plugin outlets to make changes in this part of the UI. Plugin outlets are a much more robust way to extend things, and will be more reliable across Discourse core updates.
If the existing Plugin Outlets don’t work for your use-case, then please let us know and we’ll be happy to look at introducing new ones.
In this case, you might be interested in the proposal in DEV: Add outlet and API for adding/controlling post selection buttons by keegangeorge · Pull Request #23782 · discourse/discourse · GitHub. This introduces a ‘wrapper plugin outlet’ which will allow themes/plugins to totally replace the core implementation if they need to.
This is an alternative way to render things into Plugin Outlets, yes. But it’s more of a code-style thing - it doesn’t actually introduce any new features when compared to /connectors/... files.