In an evergoing battle against an ugly icon, I found that applications can communicate with the system tray by sending X client messages. Is there a utility for spying on these messages?


Run the application under xtrace. It'll log all communications between the application and the X server, including the command to send or receive an X client message.

xtrace myapp
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  • That's kind of what I'm trying to solve - what application is putting that there? I have the class window class name: gnome-power-manager, but there is no aplication called that. There is nothing matching "power" running as a daemon. – Shawn J. Goff Jun 24 '12 at 1:14
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    @ShawnJ.Goff Trace the server side, i.e. the system tray. – Gilles 'SO- stop being evil' Jun 24 '12 at 1:18
  • Oh, and are you sure that the communication is via window events and not via dbus? – Gilles 'SO- stop being evil' Jun 24 '12 at 1:19
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    @ShawnJ.Goff gnome-power-manager is nowadays part of gnome-settings-daemon – Ulrich Dangel Jun 24 '12 at 5:22


    xev -id WINDOW_ID

will print X11 "window events". In X11, these things are called "events". (As opposed to "messages" in Microsoft Windows).

To obtain window id, use xwininfo.

man xev, man xwininfo.

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