message: Use custom tooltips on breadcrumb icons
  Fixes
  We have to track our own onHover for this, and out of safety we ensure that exactly 1 room is hovered at a time.
diff: @@ -21,6 +21,7 @@ import MatrixClientPeg from "../../../MatrixClientPeg";
  import AccessibleButton from '../elements/AccessibleButton';
  import RoomAvatar from '../avatars/RoomAvatar';
  import classNames from 'classnames';
  +import sdk from "../../../index";
  const MAX_ROOMS = 20;
  @@ -83,7 +84,24 @@ export default class RoomBreadcrumbs extends React.Component {
  dis.dispatch({action: "view_room", room_id: room.roomId});
  }
  + _onMouseEnter(room) {
  + this._onHover(room);
  + }
  +
  + _onMouseLeave(room) {
  + this._onHover(null); // clear hover states
  + }
  +
  + _onHover(room) {
  + const rooms = this.state.rooms.slice();
  + for (const r of rooms) {
  + r.hover = room && r.room.roomId === room.roomId;
  + }
  + this.setState({rooms});
  + }
  +
  render() {
  + const Tooltip = sdk.getComponent('elements.Tooltip');
  // check for collapsed here and
  // not at parent so we keep
  // rooms in our state
  @@ -92,15 +110,23 @@ export default class RoomBreadcrumbs extends React.Component {
  return null;
  }
  const rooms = this.state.rooms;
  - const avatars = rooms.map(({room, animated}, i) => {
  + const avatars = rooms.map(({room, animated, hover}, i) => {
  const isFirst = i === 0;
  const classes = classNames({
  "mx_RoomBreadcrumbs_preAnimate": isFirst && !animated,
  "mx_RoomBreadcrumbs_animate": isFirst,
  });
  +
  + let tooltip = null;
  + if (hover) {
  + tooltip = <Tooltip label={room.name} />;
  + }
  +
  return (
  - <AccessibleButton className={classes} key={room.roomId} title={room.name} onClick={() => this._viewRoom(room)}>
  + <AccessibleButton className={classes} key={room.roomId} onClick={() => this._viewRoom(room)}
  + onMouseEnter={() => this._onMouseEnter(room)} onMouseLeave={() => this._onMouseLeave(room)}>
  <RoomAvatar room={room} width={32} height={32} />
  + {tooltip}
  </AccessibleButton>
  );
  });
  