I made a PR to modernize the component. (sponsored by @davidkingham) 
Along the way, it fixes a few UX issues that I noticed.
https://github.com/paviliondev/discourse-dropdown-header/pull/11
The component could use further improvement. I might PR another time. Here are a few ones I noted:
- Replace
json_schemasetting type withobjectstype - Add an option to open a link in a new tab
- Better accessibility