show_dropdown aria-expanded applied to wrong element

[LostKobrakai]

Currently show_dropdown() applies aria-expanded to the toggled dropdown element instead of the button toggling the dropdown.

There are several widgets that can be expanded and collapsed, including menus, dialogs, and accordion panels. Each of these objects, in turn, has an interactive element that controls their opening and closing. The aria-expanded attribute is applied to this focusable, interactive control that toggles the visibility of the object.

https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Attributes/aria-expanded