How to use RegisterCommand?

[dakuenjery]

I'm trying to add a new command.
I try
RegisterCommand(name="newcmd" :config="{}" :behaviour="() => console.log('CLICK!')" extend="")
but it's not working, function is not invoked and 'CLICK' is not showed in the browser console.
The documentation does not describe how to add a new command, which fields the config object should contain and demo don't use RegisterCommand.
Can you provide a working example, please?