Wire up comboboxes

app/javascript/controllers/expandable_controller.js

@@ -0,0 +1,9 @@
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  closeOnFocusOutside(event) {
+    if (!this.element.contains(event.relatedTarget)) {
+      this.element.removeAttribute("open")
+    }
+  }
+}