QtAssistant doesn't save bookmarks when process is closed

• Launch QtAssistant process by the application:
  http://doc.qt.io/qt-5/assistant-custom-help-viewer.html#using-qt-assistant-remotely
• Create new bookmark
• Close remote process programmable by QProcess::close()
• Launch QtAssistant and see that bookmark is not saved.

Bookmarks are saved if user closes the application window from 'x'.