fix(menu): not handling keyboard events when opened by mouse

Fixes the menu keyboard interactions not working when it is opened by a click.

Fixes #4991.

e2e/components/menu-e2e.spec.ts

@@ -96,9 +96,9 @@ describe('menu', () => {
       expectFocusOn(page.items(0));
     });
 
-    it('should not focus the first item when opened with mouse', () => {
+    it('should focus the panel when opened by mouse', () => {
       page.trigger().click();
-      expectFocusOn(page.trigger());
+      expectFocusOn(page.menu());
     });
 
     it('should focus subsequent items when down arrow is pressed', () => {

src/lib/menu/menu-directive.ts

@@ -193,6 +193,14 @@ export class MdMenu implements AfterContentInit, MdMenuPanel, OnDestroy {
     this._keyManager.setFirstItemActive();
   }
 
+  /**
+   * Resets the active item in the menu. This is used when the menu is opened by mouse,
+   * allowing the user to start from the first option when pressing the down arrow.
+   */
+  resetActiveItem() {
+    this._keyManager.setActiveItem(-1);
+  }
+
   /**
    * It's necessary to set position-based classes to ensure the menu panel animation
    * folds out from the correct direction.

src/lib/menu/menu-panel.ts

@@ -19,6 +19,7 @@ export interface MdMenuPanel {
   parentMenu?: MdMenuPanel | undefined;
   direction?: Direction;
   focusFirstItem: () => void;
+  resetActiveItem: () => void;
   setPositionClasses: (x: MenuPositionX, y: MenuPositionY) => void;
   setElevation?(depth: number): void;
 }

src/lib/menu/menu-trigger.ts

@@ -239,10 +239,16 @@ export class MdMenuTrigger implements AfterViewInit, OnDestroy {
     this._setMenuElevation();
     this._setIsMenuOpen(true);
 
-    // Should only set focus if opened via the keyboard, so keyboard users can
-    // can easily navigate menu items. According to spec, mouse users should not
-    // see the focus style.
-    if (!this._openedByMouse) {
+    // If the menu was opened by mouse, we focus the root node, which allows for the keyboard
+    // interactions to work. Otherwise, if the menu was opened by keyboard, we focus the first item.
+    if (this._openedByMouse) {
+      let rootNode = this._overlayRef!.overlayElement.firstElementChild as HTMLElement;
+
+      if (rootNode) {
+        this.menu.resetActiveItem();
+        rootNode.focus();
+      }
+    } else {
       this.menu.focusFirstItem();
     }
   }

src/lib/menu/menu.html

@@ -6,6 +6,7 @@
     (click)="close.emit('click')"
     [@transformMenu]="_panelAnimationState"
     (@transformMenu.done)="_onAnimationDone($event)"
+    tabindex="-1"
     role="menu">
     <div class="mat-menu-content" [@fadeInItems]="'showing'">
       <ng-content></ng-content>

src/lib/menu/menu.scss

@@ -14,6 +14,7 @@ $mat-menu-submenu-indicator-size: 10px !default;
   @include mat-menu-positions();
   max-height: calc(100vh - #{$mat-menu-item-height});
   border-radius: $mat-menu-border-radius;
+  outline: 0;
 
   // Prevent the user from interacting while the panel is still animating.
   // This avoids issues where the user could accidentally open a sub-menu,

src/lib/menu/menu.spec.ts

@@ -29,6 +29,7 @@ import {
   dispatchMouseEvent,
   dispatchEvent,
   createKeyboardEvent,
+  dispatchFakeEvent,
 } from '@angular/cdk/testing';
 
 
@@ -173,6 +174,23 @@ describe('MdMenu', () => {
     expect(fixture.destroy.bind(fixture)).not.toThrow();
   });
 
+  it('should focus the menu panel root node when it was opened by mouse', () => {
+    const fixture = TestBed.createComponent(SimpleMenu);
+
+    fixture.detectChanges();
+
+    const triggerEl = fixture.componentInstance.triggerEl.nativeElement;
+
+    dispatchFakeEvent(triggerEl, 'mousedown');
+    triggerEl.click();
+    fixture.detectChanges();
+
+    const panel = overlayContainerElement.querySelector('.mat-menu-panel');
+
+    expect(panel).toBeTruthy('Expected the panel to be rendered.');
+    expect(document.activeElement).toBe(panel, 'Expected the panel to be focused.');
+  });
+
   describe('positions', () => {
     let fixture: ComponentFixture<PositionedMenu>;
     let panel: HTMLElement;
@@ -770,20 +788,6 @@ describe('MdMenu', () => {
           .toBe(true, 'Expected focus to be back inside the root menu');
     });
 
-    it('should not shift focus to the sub-menu when it was opened by hover', () => {
-      compileTestComponent();
-      instance.rootTriggerEl.nativeElement.click();
-      fixture.detectChanges();
-
-      const levelOneTrigger = overlay.querySelector('#level-one-trigger')! as HTMLElement;
-
-      dispatchMouseEvent(levelOneTrigger, 'mouseenter');
-      fixture.detectChanges();
-
-      expect(overlay.querySelectorAll('.mat-menu-panel')[1].contains(document.activeElement))
-          .toBe(false, 'Expected focus to not be inside the nested menu');
-    });
-
     it('should position the sub-menu to the right edge of the trigger in ltr', () => {
       compileTestComponent();
       instance.rootTriggerEl.nativeElement.style.position = 'fixed';
@@ -1057,6 +1061,7 @@ class CustomMenuPanel implements MdMenuPanel {
   @ViewChild(TemplateRef) templateRef: TemplateRef<any>;
   @Output() close = new EventEmitter<void | 'click' | 'keydown'>();
   focusFirstItem = () => {};
+  resetActiveItem = () => {};
   setPositionClasses = () => {};
 }