Description
What feature are you requesting?
Listbox/Select should support multiple and size properties, which will allow users to choose more than one option at a time. This will require support for related ARIA attributes as well as keyboard navigation changes. See https://www.w3.org/TR/wai-aria-practices-1.1/#listbox_roles_states_props for more info on ARIA role support.
From a presentation perspective, a select in multi-mode should look similar to our current listbox component. The button and its indicator should not be displayed, and the dropdown should be presented. The ability to open and close the select should have no effect in multi-mode.
The size property should be added to allow for changing the number of visible options. I'm not sure if this property should affect the listbox when in single mode. It's also unclear how this property should affect a listbox with arbitrary slotted content like containers, images, horizontal rules, etc.