message: add a hideCancel flag as some things have own cancel etc on RoomHeader
diff: @@ -1622,6 +1622,7 @@ module.exports = React.createClass({
  }
  let aux = null;
  + let hideCancel = false;
  if (this.state.forwardingEvent !== null) {
  aux = <ForwardMessage onCancelClick={this.onCancelClick} currentRoomId={this.state.room.roomId} mxEvent={this.state.forwardingEvent} />;
  } else if (this.state.editingRoomSettings) {
  @@ -1629,6 +1630,7 @@ module.exports = React.createClass({
  } else if (this.state.uploadingRoomSettings) {
  aux = <Loader/>;
  } else if (this.state.searching) {
  + hideCancel = true; // has own cancel
  aux = <SearchBar ref="search_bar" searchInProgress={this.state.searchInProgress } onCancelClick={this.onCancelSearchClick} onSearch={this.onSearch}/>;
  } else if (!myMember || myMember.membership !== "join") {
  // We do have a room object for this room, but we're not currently in it.
  @@ -1641,6 +1643,7 @@ module.exports = React.createClass({
  if (this.props.thirdPartyInvite) {
  invitedEmail = this.props.thirdPartyInvite.invitedEmail;
  }
  + hideCancel = true;
  aux = (
  <RoomPreviewBar onJoinClick={this.onJoinButtonClicked}
  onForgetClick={ this.onForgetClick }
  @@ -1787,13 +1790,10 @@ module.exports = React.createClass({
  onSearchClick={this.onSearchClick}
  onSettingsClick={this.onSettingsClick}
  onSaveClick={this.onSettingsSaveClick}
  - onCancelClick={aux ? this.onCancelClick : null}
  - onForgetClick={
  - (myMember && myMember.membership === "leave") ? this.onForgetClick : null
  - }
  - onLeaveClick={
  - (myMember && myMember.membership === "join") ? this.onLeaveClick : null
  - } />
  + onCancelClick={(aux && !hideCancel) ? this.onCancelClick : null}
  + onForgetClick={(myMember && myMember.membership === "leave") ? this.onForgetClick : null}
  + onLeaveClick={(myMember && myMember.membership === "join") ? this.onLeaveClick : null}
  + />
  { auxPanel }
  { topUnreadMessagesBar }
  { messagePanel }
  