fix: address more feedback

Author: crisbeto

src/lib/core/a11y/focus-trap.ts

@@ -29,7 +29,7 @@ export class FocusTrap {
     this._enabled = val;
     this._startAnchor.tabIndex = this._endAnchor.tabIndex = this._enabled ? 0 : -1;
   }
-  private _enabled: boolean = false;
+  private _enabled: boolean = true;
 
   constructor(
     private _element: HTMLElement,
@@ -42,9 +42,7 @@ export class FocusTrap {
     }
   }
 
-  /**
-   * Destroys the focus trap by cleaning up the anchors.
-   */
+  /** Destroys the focus trap by cleaning up the anchors. */
   destroy() {
     if (this._startAnchor.parentNode) {
       this._startAnchor.parentNode.removeChild(this._startAnchor);
@@ -74,24 +72,22 @@ export class FocusTrap {
   }
 
   /**
-   * Waits for microtask queue to empty, then focuses the first tabbable element within the focus
-   * trap region.
+   * Waits for microtask queue to empty, then focuses
+   * the first tabbable element within the focus trap region.
    */
   focusFirstTabbableElementWhenReady() {
     this._ngZone.onMicrotaskEmpty.first().subscribe(() => this.focusFirstTabbableElement());
   }
 
   /**
-   * Waits for microtask queue to empty, then focuses the last tabbable element within the focus
-   * trap region.
+   * Waits for microtask queue to empty, then focuses
+   * the last tabbable element within the focus trap region.
    */
   focusLastTabbableElementWhenReady() {
     this._ngZone.onMicrotaskEmpty.first().subscribe(() => this.focusLastTabbableElement());
   }
 
-  /**
-   * Focuses the first tabbable element within the focus trap region.
-   */
+  /** Focuses the first tabbable element within the focus trap region. */
   focusFirstTabbableElement() {
     let redirectToElement = this._element.querySelector('[cdk-focus-start]') as HTMLElement ||
                             this._getFirstTabbableElement(this._element);
@@ -101,9 +97,7 @@ export class FocusTrap {
     }
   }
 
-  /**
-   * Focuses the last tabbable element within the focus trap region.
-   */
+  /** Focuses the last tabbable element within the focus trap region. */
   focusLastTabbableElement() {
     let focusTargets = this._element.querySelectorAll('[cdk-focus-end]');
     let redirectToElement: HTMLElement = null;
@@ -154,24 +148,23 @@ export class FocusTrap {
     return null;
   }
 
+  /** Creates an anchor element. */
   private _createAnchor(): HTMLElement {
     let anchor = document.createElement('div');
-    anchor.tabIndex = 0;
+    anchor.tabIndex = this._enabled ? 0 : -1;
     anchor.classList.add('cdk-visually-hidden');
     anchor.classList.add('cdk-focus-trap-anchor');
     return anchor;
   }
 }
 
 
-/**
- * Factory that allows easy instantiation of focus traps.
- */
+/** Factory that allows easy instantiation of focus traps. */
 @Injectable()
 export class FocusTrapFactory {
   constructor(private _checker: InteractivityChecker, private _ngZone: NgZone) { }
 
-  attach(element: HTMLElement, deferAnchors = false): FocusTrap {
+  create(element: HTMLElement, deferAnchors = false): FocusTrap {
     return new FocusTrap(element, this._checker, this._ngZone, deferAnchors);
   }
 }
@@ -195,7 +188,7 @@ export class FocusTrapDeprecatedDirective implements OnDestroy, AfterContentInit
   }
 
   constructor(private _elementRef: ElementRef, private _focusTrapFactory: FocusTrapFactory) {
-    this.focusTrap = this._focusTrapFactory.attach(this._elementRef.nativeElement, true);
+    this.focusTrap = this._focusTrapFactory.create(this._elementRef.nativeElement, true);
   }
 
   ngOnDestroy() {
@@ -208,9 +201,7 @@ export class FocusTrapDeprecatedDirective implements OnDestroy, AfterContentInit
 }
 
 
-/**
- * Directive for trapping focus within a region.
- */
+/** Directive for trapping focus within a region. */
 @Directive({
   selector: '[cdkTrapFocus]'
 })
@@ -223,7 +214,7 @@ export class FocusTrapDirective implements OnDestroy, AfterContentInit {
   set enabled(val: boolean) { this.focusTrap.enabled = val; }
 
   constructor(private _elementRef: ElementRef, private _focusTrapFactory: FocusTrapFactory) {
-    this.focusTrap = this._focusTrapFactory.attach(this._elementRef.nativeElement, true);
+    this.focusTrap = this._focusTrapFactory.create(this._elementRef.nativeElement, true);
   }
 
   ngOnDestroy() {

src/lib/dialog/dialog-container.ts

@@ -90,7 +90,7 @@ export class MdDialogContainer extends BasePortalHost implements OnDestroy {
    */
   private _trapFocus() {
     if (!this._focusTrap) {
-      this._focusTrap = this._focusTrapFactory.attach(this._elementRef.nativeElement);
+      this._focusTrap = this._focusTrapFactory.create(this._elementRef.nativeElement);
     }
 
     // If were to attempt to focus immediately, then the content of the dialog would not yet be

src/lib/sidenav/sidenav.ts

@@ -172,7 +172,7 @@ export class MdSidenav implements AfterContentInit, OnDestroy {
   }
 
   ngAfterContentInit() {
-    this._focusTrap = this._focusTrapFactory.attach(this._elementRef.nativeElement);
+    this._focusTrap = this._focusTrapFactory.create(this._elementRef.nativeElement);
     this._focusTrap.enabled = this.isFocusTrapEnabled;
 
     // This can happen when the sidenav is set to opened in