This is the DOM (Document Object Model) extension that @richard had started, and was used to build the badge. We’ve carved it out and we’ll continue to improve it. This extension can be used to build user interfaces, menus, buttons, etc…
Strange: the dom tool installed with link from Github but then went away. Is the extension hidden in tools somewhere: https://makecode.com/_5hHAWi7puhRR
The Dom blocks are not really ready. You should see a “Dom” toolbox opened there.