How do I add the "settings" dropdown to a custom widget ?

https://jazz.net/wiki/bin/view/Main/RMExtensionsMain 

All is good, I made it an OpenSocial widget and I also made it into a catalog. 

However I saw a built in widget that has a settings dropdown. I tried looking for how to do this in the documentation but found nothing. Does anyone know how to make my own settings for a custom widget ? 

See the url screenshot below for what I am talking about. (don't have enough reputation to attach an image, sorry)

https://pasteboard.co/GOhQH4B.png - Widget with Setting dropdown

https://pasteboard.co/GOhR5eh.png - Custom Hello World widget without the settting dropdown.