Set Himawari as dekstop and lockscreen

himawari-workaround.sh

#!/bin/bash
# http://bit.ly/2ines3u

# Wallpaper's directory.
dir="${HOME}/.cache/himawaripy/"

# export DBUS_SESSION_BUS_ADDRESS environment variable
PID=$(pgrep gnome-session)
export DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ | cut -d= -f2-)

# Random wallpaper.
wallpaper=`find "${dir}" -type f | shuf -n1`

echo "Set wallpaper: ${wallpaper}"

# Change wallpaper.
# http://bit.ly/HYEU9H
gsettings set org.gnome.desktop.background picture-options "scaled"
gsettings set org.gnome.desktop.background picture-uri "file://${wallpaper}"
gsettings set org.gnome.desktop.background primary-color "#000000"
gsettings set org.gnome.desktop.background secondary-color "#000000"
gsettings set org.gnome.desktop.background color-shading-type "solid"

gsettings set org.gnome.desktop.screensaver picture-options "scaled"
gsettings set org.gnome.desktop.screensaver picture-uri "file://${wallpaper}"
gsettings set org.gnome.desktop.screensaver primary-color "#000000"
gsettings set org.gnome.desktop.screensaver secondary-color "#000000"
gsettings set org.gnome.desktop.screensaver color-shading-type "solid"

cp $wallpaper /usr/share/backgrounds/himawari.png

Also, edit the file

sudo gedit /usr/share/gnome-shell/theme/ubuntu.css

and change #lockDialogGroup css to:

#lockDialogGroup {
  background: #000000 url(file:///usr/share/backgrounds/himawari.png);
  background-repeat: no-repeat;
  background-size: contain;
  background-position: center;
}

Note 1: You may need to give access to /usr/share/backgrounds/ folder:

sudo chmod 777 /usr/share/backgrounds/

Note 2: You may need to add path variable to crontab: