How to create the same button and popup like on main vaadin page?
This button on right side with “v” symbol. Click on this button will show popup which
is showing over the page and not moving up/down with the entire page.
I think you might mean the [Chat]
(https://vaadin.com/directory/component/chat) component, available only for Vaadin Prime customers.
If you are solely interested in how to have something stay at the same position no matter how you scoll - this is done with CSS position: fixed;. You can do this to any component you like