System tray (notification area) icons are not shown on unity-session and gnome-classic

[Norbert]

Steps to reproduce:
1. Install Ubuntu 17.10
2. Install application which places its icon to the system tray (notification area) such as `hplip` or `transmission`
3. Try to find application icon in the system tray (notification area)

Expected results:
Application icon is placed and shown in the system tray (notification area)

Actual results:
Application icon is not placed and not shown in the system tray (notification area)

Info:
$ export | grep "SESSION\|DESK"
declare -x DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/1000/bus"
declare -x DESKTOP_AUTOSTART_ID="1017f889114f44fd14150394394580989400000102050008"
declare -x DESKTOP_SESSION="ubuntu-xorg"
declare -x GDMSESSION="ubuntu-xorg"
declare -x GNOME_DESKTOP_SESSION_ID="this-is-deprecated"
declare -x GNOME_SESSION_XDG_SESSION_PATH=""
declare -x GNOME_SHELL_SESSION_MODE="ubuntu"
declare -x SESSION_MANAGER="local/artful:@/tmp/.ICE-unix/10205,unix/artful:/tmp/.ICE-unix/10205"
declare -x XDG_CURRENT_DESKTOP="ubuntu:GNOME"
declare -x XDG_SESSION_DESKTOP="ubuntu-xorg"
declare -x XDG_SESSION_ID="11"
declare -x XDG_SESSION_TYPE="x11"

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: ubuntu-session 3.25.90-0ubuntu2
ProcVersionSignature: Ubuntu 4.12.0-11.12-generic 4.12.5
Uname: Linux 4.12.0-11-generic i686
ApportVersion: 2.20.6-0ubuntu7
Architecture: i386
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 28 21:13:32 2017
InstallationDate: Installed on 2017-08-26 (1 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha i386 (20170826)
SourcePackage: gnome-session
UpgradeStatus: No upgrade log present (probably fresh install)

[Norbert (nrbrtx)]

Same on Unity Wayland.

[Norbert (nrbrtx)]

Same on GNOME Classic.

[Sebastien Bacher (seb128)]

Thank you for your bug report, the notification area is in the bottom left corner under a an arrow/drawer, indicators should be listed in the panel with the appindicator extension which is installed by default now

[Matthew Paul Thomas (mpt)]

Ubuntu abolished the notification area in 2011, in favor of application indicators, and reviving it would be a regression. <https://design.canonical.com/2010/04/notification-area/>

Transmission and hplip both adopted application indicators years ago, so there is no need to show the notification area for their sake.

[Norbert (nrbrtx)]

With all latest updates hplip icon is in place (as appindicator) on Ubuntu session. Thank you!

[Norbert (nrbrtx)]

But hplip icon is not shown on GNOME Classic session.

[Daniel van Vugt (vanvugt)]

Sounds like it's fixed?

[Norbert (nrbrtx)]

In final 17.10 bug is fixed. Thank you!