@petrus: have you looked at re-com?

re-com doesn't have exactly that component, although we were tempted when we wrote the dropdown component (which was inspired by bootstrap-chosen: http://alxlit.name/bootstrap-chosen). The closest thing we have to a multi-select is selection-list: http://re-demo.s3-website-ap-southeast-2.amazonaws.com/#/lists, but I suspect you have a long list and want a convenient way to see a small number of selections from it, wherever they may be within the list.