message: also warn when quitting mid-call
diff: @@ -100,6 +100,10 @@ module.exports = React.createClass({
  this._checkSize();
  },
  + componentDidMount: function() {
  + window.addEventListener('beforeunload', this.onPageUnload);
  + },
  +
  componentDidUpdate: function() {
  this._checkSize();
  },
  @@ -111,6 +115,7 @@ module.exports = React.createClass({
  client.removeListener("sync", this.onSyncStateChange);
  client.removeListener("RoomMember.typing", this.onRoomMemberTyping);
  }
  + window.removeEventListener('beforeunload', this.onPageUnload);
  },
  onSyncStateChange: function(state, prevState) {
  @@ -128,6 +133,13 @@ module.exports = React.createClass({
  });
  },
  + onPageUnload(event) {
  + if (this.props.hasActiveCall) {
  + return event.returnValue =
  + 'You seem to be in a call, are you sure you want to quit?';
  + }
  + },
  +
  // Check whether current size is greater than 0, if yes call props.onVisible
  _checkSize: function () {
  if (this.props.onVisible && this._getSize()) {
  