Created attachment 5066 strace output for mount/umount of USB-device in thunar-1.6.2 Following issue described in bug #10154 Mount via Thunar works fine. Umount really umounts device (mount command don't list it in mounted devices list) fails to finish (endlessly shows rotating circle). This issue was seen both on USB and optical drive mount. Eject for optical drive works OK. Strace for umount of USB device is attached. P.S. As a temporary workaround to umount device I use xfce-extra/xfce4-mount-plugin.
Works for me in thunar-1.6.6.