How is the built-in controls made?

[Jan Sælid]

Hi again Eric
(Thanks for the patience)

I mean the "Tab panel" that you drag from tools to your stack when you want 
a tab-panel. When I look at the properties
this is a button. How is this possible? If you want to do build a tab panel 
from the ground up you usually have make a group or multiple cards.

What is the "inner workings" going on here?

(I hope this is clearer....Suddenly my confidence in English went on a 
trip....)

WR
Jan