Add option to toggle multiselect choices inside dropdown

[coreyharrison]

Is it possible to add the option to toggle choices in multi-select mode from the dropdown?
My use case is when we have close-on-select and remove-on-select both false it would be a better user experience if we could simply toggle selected items from the dropdown rather than having to remove the tags.

In my case we might have countries that we are adding and if the user adds a country by accident they would then have to remove it from the list and then go back and find where they were up to in the dropdown list.