message: Handle ARROW_RIGHT on group node in treelist as per aria suggestions
diff: @@ -133,15 +133,51 @@ const RoomSubList = createReactClass({
  // Prevent LeftPanel handling Tab if focus is on the sublist header itself
  ev.stopPropagation();
  break;
  - case Key.ARROW_RIGHT:
  + case Key.ARROW_RIGHT: {
  ev.stopPropagation();
  if (this.state.hidden && !this.props.forceExpand) {
  + // sublist is collapsed, expand it
  this.onClick();
  + } else if (!this.props.forceExpand) {
  + // sublist is expanded, go to first room
  + let element = document.activeElement;
  + let descending = true;
  + let classes;
  +
  + do {
  + const child = element.firstElementChild;
  + const sibling = element.nextElementSibling;
  +
  + if (descending) {
  + if (child) {
  + element = child;
  + } else if (sibling) {
  + element = sibling;
  } else {
  - // TODO go to first element in subtree
  + descending = false;
  + element = element.parentElement;
  + }
  + } else {
  + if (sibling) {
  + element = sibling;
  + descending = true;
  + } else {
  + element = element.parentElement;
  + }
  + }
  +
  + if (element) {
  + classes = element.classList;
  + }
  + } while (element && !classes.contains("mx_RoomTile"));
  +
  + if (element) {
  + element.focus();
  + }
  }
  break;
  }
  + }
  },
  onKeyDown: function(ev) {
  