prevent fake pointer like events from PDOM root, see phetsims/a11y-re…

…search#133

js/accessibility/AccessiblePeer.js

@@ -32,11 +32,6 @@ define( function( require ) {
   var LABEL_TAG = AccessibilityUtil.TAGS.LABEL;
   var INPUT_TAG = AccessibilityUtil.TAGS.INPUT;
 
-  // On certain screen readers, the assistive device may send "fake" pointer events to the browser when only using
-  // a keyboard. We want to handle these as keyboard or alternative events exclusively and not through scenery's
-  // pointer system. See https://github.com/phetsims/scenery/issues/852#issuecomment-467994327
-  var BLOCKED_EVENTS = [ 'touchstart', 'touchend', 'mousedown', 'mouseup' ];
-
   // DOM observers that apply new CSS transformations are triggered when children, or inner content change. Updating
   // style/positioning of the element will change attributes so we can't observe those changes since it would trigger
   // the MutationObserver infinitely.
@@ -199,16 +194,6 @@ define( function( require ) {
         trailId: uniqueId
       } );
 
-      // Block any fake pointer events that will be sourced on the primary sibling when a screen reader is in use.
-      // Screen readers inconsistently send these events and we want all pointer events to go through
-      // scenery's pointer input system and the display div, never the PDOM
-      for ( var i = 0; i < BLOCKED_EVENTS.length; i++ ) {
-        this._primarySibling.addEventListener( BLOCKED_EVENTS[ i ], function( event ) {
-          event.preventDefault();
-          event.stopPropagation();
-        } );
-      }
-
       // create the container parent for the dom siblings
       if ( options.containerTagName ) {
         this._containerParent = AccessibilityUtil.createElement( options.containerTagName, false, {

js/input/Input.js

@@ -156,6 +156,11 @@ define( require => {
 
   const TARGET_SUBSTITUTE_KEY = 'targetSubstitute';
 
+  // Some assistive devices may send "fake" pointer like events to the browser when only using
+  // a keyboard. We want to handle these as keyboard or alternative events exclusively and not through scenery's
+  // pointer system. See https://github.com/phetsims/scenery/issues/852#issuecomment-467994327
+  var BLOCKED_ACCESSIBLE_EVENTS = [ 'touchstart', 'touchend', 'mousedown', 'mouseup' ];
+
   /**
    * An input controller for a specific Display.
    * @constructor
@@ -768,6 +773,16 @@ define( require => {
           }, accessibleEventOptions );
         } );
 
+        // Block any fake pointer events that may be sourced on the a PDOM element when a screen reader is in use.
+        // Screen readers inconsistently send these fake "pointer" like events to DOM elements and we want
+        // all pointer events to go through scenery's pointer input system and the display div, never the PDOM
+        for ( var i = 0; i < BLOCKED_ACCESSIBLE_EVENTS.length; i++ ) {
+          this.display.accessibleDOMElement.addEventListener( BLOCKED_ACCESSIBLE_EVENTS[ i ], function( event ) {
+            event.preventDefault();
+            event.stopPropagation();
+          } );
+        }
+
         // Add a listener to the document body that will capture any keydown for a11y before focus is in this display.
         document.body.addEventListener( 'keydown', this.handleDocumentKeydown.bind( this ) );
       }