Comment 1 for bug 1360652

Qt 5's system tray functionality on linux is very buggy, see for example
http://stackoverflow.com/questions/25314391/system-tray-icon-doesnt-show-in-qt5-linux-lxde

It works with some window managers/desktop environments and not with
others.

Until that is fixed, I suggest disabling the tray icon in preferences
(it defaults to disabled). I might look into permanently removing
system tray functionality on linux in calibre 2.0

 status invalid