That is a demo of window frame constructor. It was made as a prototype of a large CAD system.
The demo is made with react, konva, and react-konva.
If you are interested in similar product for your company - get in touch.
Instructions: You can select section and split it into several child sections. Also you can set sash type of a section.
<iframe src="https://codesandbox.io/embed/github/konvajs/site/tree/master/react-demos/window-frame-design-app?hidenavigation=1&view=split&fontsize=10" style="width:100%; height:500px; border:0; border-radius: 4px; overflow:hidden;" sandbox="allow-modals allow-forms allow-popups allow-scripts allow-same-origin"></iframe>