when I close thunar it still remain as process, i could see him in taskmanager. I'm using an external monitor, so i need to kill thunar to have a better visualization, because it starts automatically, even if in the "automatically started application" window it is not listed.
That's not a bug. Thunar also acts as a D-Bus service for xfdesktop and the trash panel plugin. Having it still running means that new windows will show up almost instantly, which is a good thing. If you don't want this, you can either compile Thunar without D-Bus suppport or remove org.xfce.FileManager.service and org.xfce.Thunar.service from /usr/share/dbus-1/services/. Anyway, this is not a bug.