Preference\Openbox Cobfig Manager - Clearlook-3.4
Preference\Customize Look and Feel\Widget - Clearlook, IconTheme - GNOME
Preference\Desktop Preference - Wallpaper mode - Fill with background color only
System Tools\LightDM GTK+ Greeter setting - Image - none

Grub - /etc/default/grub
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=5
GRUB_CMDLINE_LINUX_DEFAULT=""
update-grub

screen locked problem:
https://lnbu.jimdo.com/turorials/lubuntu/screen-lock-deactivation/
https://askubuntu.com/questions/64086/how-can-i-change-or-install-screensavers
https://fitzcarraldoblog.wordpress.com/2018/04/20/getting-the-lock-screen-to-work-properly-when-resuming-from-suspend-to-ram-with-multiple-sessions-in-lubuntu-17-10/
https://unix.stackexchange.com/questions/442057/ubuntu-18-04-wont-wake-after-screen-lock-and-blank-suspend-sleep
sudo apt-get remove light-locker
sudo apt-get install xscreensaver