How can we create a treeview toolbox in blockly as in image any sample code or need guide to the docs

In the image left is toolbox,when we select the option in tool box it opens a flyout in workspace as in the right can't understand the procedure in docs need help to integrate it using html javascript

Blocky has provided the implementation method of treeView toolbox. Refer to this page: https://blockly-demo.appspot.com/static/demos/toolbox/index.html

After you implement the treeView toolbox, you just need to change the CSS style of each lable to achieve the desired effect.