HPLIP hp-systray menu is not shown on clean Ubuntu MATE 18.04.1 installation

Support & Help Requests
1

I have clean installation of Ubuntu MATE 18.04.1 LTS amd64 without PPAs.
I have installed HPLIP into it with

sudo apt install hplip-gui

then rebooted.

As the result I got hp-systray in top MATE Panel, but its dropdown menu is not functional:

1
hplip-18.04.1.png672×651 65.3 KB

Some information:

$ dpkg -l | grep hplip
ii  hplip                                 3.17.10+repack0-5                   amd64        HP Linux Printing and Imaging System (HPLIP)
ii  hplip-data                            3.17.10+repack0-5                   all          HP Linux Printing and Imaging - data files
ii  hplip-gui                             3.17.10+repack0-5                   all          HP Linux Printing and Imaging - GUI utilities (Qt-based)

I reported bug 1810745 to LaunchPad.

Why does this happening?

2

Seems to be a bug.

I posted my temporary solution on AskUbuntu:

The autostart file from hplip-gui is located in /etc/xdg/autostart/hplip-systray.desktop.

To fix the menu display we need to launch hplip with help of DBus (as in DropBox case) by creating and editing this file:

killall hp-systray
rm ~/.hplip/hp-systray.lock
mkdir -p ~/.config/autostart/
cp /etc/xdg/autostart/hplip-systray.desktop ~/.config/autostart/
sed -i "s/hp-systray -x/dbus-launch hp-systray -x/" ~/.config/autostart/hplip-systray.desktop

and then reboot and enjoy:

hp-systray with dropdown menu

Notes:
This method is useful for 18.04 LTS, 18.10 and 19.04. It is a temporary fix for bug 1810745.