How to display the KDE system tray icons on LXDE panel?

Question

With KDE, I sometime need to close/kill KDE (plasmashell) to have more available system resources, while doing so I run lxpanel on its own to have a minimal panel while KDE Plasma is closed. This does work flawlessly but the system tray.

On the LXDE panel (lxpanel) I have added the system tray applet and did get the tray to work only when I launch application with the following commands:

# is currently KDE even if plasmashell is closed
export XDG_CURRENT_DESKTOP=LXDE
dbus-launch app_using_tray

Is there a way to have the currently running tray applications displayed on lxpanel? or is there any alternative that would permit to access to those application while plasmashell is closed? How to display the KDE system tray icons when plasmashell is replaced temporarily with LXDE panel?

Answer 1

X Tray System:

On most desktops the tray icon system can be replaced with other system like stalonetray, trayer or wmsystemtray while doing so, the tray system needs to be registered as the used tray system, for KDE details can be found here this is why dbus-launch and XDG_CURRENT_DESKTOP are required when the alternative tray is not the default.

LXDE Panel With KDE:

Indeed LXDE panel (lxpanel) can be run along with other desktop like KDE... since the purpose here is just to switch to a lighter desktop when the usage require more ressources, the tray problem can be fixed with plasmawindowed this will permit to run org.kde.plasma.systemtray in a windowed mode in a single instance and thus have the tray system accessible while using lxpanel, further more windows rules can be used to arrange it as a panel (without the decoration etc.) this bash script can be used to switch the desktop to a lighter one, and closing it would be done with ctrl+c:

#!/bin/bash

kill_panel() {
    killall lxpanel
}

trap 'kill_panel' SIGINT

/usr/bin/lxpanel&
plasmawindowed org.kde.plasma.systemtray

Additional infos about system tray