Remove buttonIndex

index.bs

@@ -1957,22 +1957,18 @@ XRInputSourceEvent {#xrinputsourceevent-interface}
 interface XRInputSourceEvent : Event {
   [SameObject] readonly attribute XRFrame frame;
   [SameObject] readonly attribute XRInputSource inputSource;
-  [SameObject] readonly attribute long? buttonIndex;
 };
 
 dictionary XRInputSourceEventInit : EventInit {
   required XRFrame frame;
   required XRInputSource inputSource;
-  long? buttonIndex = null;
 };
 </pre>
 
 The <dfn attribute for="XRInputSourceEvent">inputSource</dfn> attribute indicates the {{XRInputSource}} that generated this event.
 
 The <dfn attribute for="XRInputSourceEvent">frame</dfn> attribute is an {{XRFrame}} that corresponds with the time that the event took place. It may represent historical data. Any {{XRViewerPose}} queried from the {{XRInputSourceEvent/frame}} MUST have an empty {{XRViewerPose/views}} array.
 
-The <dfn attribute for="XRInputSourceEvent">buttonIndex</dfn> attribute indicates the index of the button in the {{Gamepad/buttons}} array of the {{XRInputSourceEvent/inputSource}}'s {{XRInputSource/gamepad}} that caused the event to be generated. If the {{XRInputSource/gamepad}} is <code>null</code> or the event was not generated by a button interaction the values MUST be <code>null</code>.
-
 <div class="algorithm" data-algorithm="fire-input-source-event">
 
 When the user agent fires an {{XRInputSourceEvent}} |event| it MUST run the following steps:

input-explainer.md

@@ -330,7 +330,7 @@ function onXRFrame(timestamp, frame) {
 }
 ```
 
-If the application includes interactions that require user activation (such as starting media playback), the application can listen to the `XRInputSource`s `select` events, which fire for every pressed and released button on the controller. When triggered by a controller input, the `XRInputSourceEvent` will include a `buttonIndex` other than `-1` to indicate which button on the gamepad triggered the event.
+If the application includes interactions that require user activation (such as starting media playback), the application can listen to the `XRInputSource`s `select` events, which fire for the primary button on the controller.
 
 The UA may update the `gamepad` state at any point, but it must remain constant while running a batch of `XRSession` `requestAnimationFrame` callbacks or event callbacks which provide an `XRFrame`.
 
@@ -462,12 +462,10 @@ dictionary XRInputSourceChangeEventInit : EventInit {
 interface XRInputSourceEvent : Event {
   readonly attribute XRFrame frame;
   readonly attribute XRInputSource inputSource;
-  readonly attribute long buttonIndex;
 };
 
 dictionary XRInputSourceEventInit : EventInit {
   required XRFrame frame;
   required XRInputSource inputSource;
-  long buttonIndex = -1;
 };
 ```