message: fix: send displayed marker only for private chats
  related to
diff: @@ -285,6 +285,10 @@ export default class ChatMarkersPlugin extends AbstractPlugin {
  }
  private chatWindowInitializedHook(chatWindow: ChatWindow) {
  + if (chatWindow.getContact().isGroupChat()) {
  + return;
  + }
  +
  let windowElement = chatWindow.getDom().find('.jsxc-message-input');
  windowElement.on('focus', () => this.onChatWindowFocus(chatWindow));
  