Fixes dropdown closing on tab key (#2371)

* fix(sl-menu): tabbing closes the dropdown when it's open

* fix(arbitrary content): tabbing closes the dropdown when it's open

* feat: add pr suggestions

src/components/dropdown/dropdown.component.ts

@@ -1,6 +1,7 @@
 import { animateTo, stopAnimations } from '../../internal/animate.js';
 import { classMap } from 'lit/directives/class-map.js';
 import { getAnimation, setDefaultAnimation } from '../../utilities/animation-registry.js';
+import { getDeepestActiveElement } from '../../internal/active-elements.js';
 import { getTabbableBoundary } from '../../internal/tabbable.js';
 import { html } from 'lit';
 import { ifDefined } from 'lit/directives/if-defined.js';
@@ -175,6 +176,20 @@ export default class SlDropdown extends ShoelaceElement {
         return;
       }
 
+      const computeClosestContaining = (element: Element | null | undefined, tagName: string): Element | null => {
+        if (!element) return null;
+
+        const closest = element.closest(tagName);
+        if (closest) return closest;
+
+        const rootNode = element.getRootNode();
+        if (rootNode instanceof ShadowRoot) {
+          return computeClosestContaining(rootNode.host, tagName);
+        }
+
+        return null;
+      };
+
       // Tabbing outside of the containing element closes the panel
       //
       // If the dropdown is used within a shadow DOM, we need to obtain the activeElement within that shadowRoot,
@@ -182,12 +197,13 @@ export default class SlDropdown extends ShoelaceElement {
       setTimeout(() => {
         const activeElement =
           this.containingElement?.getRootNode() instanceof ShadowRoot
-            ? document.activeElement?.shadowRoot?.activeElement
+            ? getDeepestActiveElement()
             : document.activeElement;
 
         if (
           !this.containingElement ||
-          activeElement?.closest(this.containingElement.tagName.toLowerCase()) !== this.containingElement
+          computeClosestContaining(activeElement, this.containingElement.tagName.toLowerCase()) !==
+            this.containingElement
         ) {
           this.hide();
         }

src/components/dropdown/dropdown.test.ts

@@ -1,6 +1,8 @@
 import '../../../dist/shoelace.js';
 import { clickOnElement } from '../../internal/test.js';
+import { customElement } from 'lit/decorators.js';
 import { expect, fixture, html, waitUntil } from '@open-wc/testing';
+import { LitElement } from 'lit';
 import { sendKeys, sendMouse } from '@web/test-runner-commands';
 import sinon from 'sinon';
 import type SlDropdown from './dropdown.js';
@@ -354,4 +356,99 @@ describe('<sl-dropdown>', () => {
 
     expect(el.open).to.be.false;
   });
+
+  describe('when a sl-menu is provided and the dropdown is opened', () => {
+    before(() => {
+      @customElement('custom-wrapper')
+      class Wrapper extends LitElement {
+        render() {
+          return html`<nested-dropdown></nested-dropdown>`;
+        }
+      }
+      // eslint-disable-next-line chai-friendly/no-unused-expressions
+      Wrapper;
+
+      @customElement('nested-dropdown')
+      class NestedDropdown extends LitElement {
+        render() {
+          return html`
+            <sl-dropdown>
+              <sl-button slot="trigger" caret>Toggle</sl-button>
+              <sl-menu>
+                <sl-menu-item>Item 1</sl-menu-item>
+              </sl-menu>
+            </sl-dropdown>
+          `;
+        }
+      }
+      // eslint-disable-next-line chai-friendly/no-unused-expressions
+      NestedDropdown;
+    });
+
+    it('should remain open on tab key', async () => {
+      const el = await fixture<SlDropdown>(html`<custom-wrapper></custom-wrapper>`);
+
+      const dropdown = el.shadowRoot!.querySelector('nested-dropdown')!.shadowRoot!.querySelector('sl-dropdown')!;
+
+      const trigger = dropdown.querySelector('sl-button')!;
+
+      trigger.focus();
+      await dropdown.updateComplete;
+      await sendKeys({ press: 'Enter' });
+      await dropdown.updateComplete;
+      await sendKeys({ press: 'Tab' });
+      await dropdown.updateComplete;
+
+      expect(dropdown.open).to.be.true;
+    });
+  });
+
+  describe('when arbitrary content is provided and the dropdown is opened', () => {
+    before(() => {
+      @customElement('custom-wrapper-arbitrary')
+      class WrapperArbitrary extends LitElement {
+        render() {
+          return html`<nested-dropdown-arbitrary></nested-dropdown-arbitrary>`;
+        }
+      }
+      // eslint-disable-next-line chai-friendly/no-unused-expressions
+      WrapperArbitrary;
+
+      @customElement('nested-dropdown-arbitrary')
+      class NestedDropdownArbitrary extends LitElement {
+        render() {
+          return html`
+            <sl-dropdown>
+              <sl-button slot="trigger" caret>Toggle</sl-button>
+              <ul>
+                <li><a href="/settings">Settings</a></li>
+                <li><a href="/profile">Profile</a></li>
+              </ul>
+            </sl-dropdown>
+          `;
+        }
+      }
+      // eslint-disable-next-line chai-friendly/no-unused-expressions
+      NestedDropdownArbitrary;
+    });
+
+    it('should remain open on tab key', async () => {
+      const el = await fixture<SlDropdown>(html`<custom-wrapper-arbitrary></custom-wrapper-arbitrary>`);
+
+      const dropdown = el
+        .shadowRoot!.querySelector('nested-dropdown-arbitrary')!
+        .shadowRoot!.querySelector('sl-dropdown')!;
+
+      const trigger = dropdown.querySelector('sl-button')!;
+
+      trigger.focus();
+      await dropdown.updateComplete;
+      await sendKeys({ press: 'Enter' });
+      await dropdown.updateComplete;
+      await sendKeys({ press: 'Tab' });
+      await dropdown.updateComplete;
+
+      expect(dropdown.open).to.be.true;
+    });
+  });
 });