QSystemTrayIcon - how to make one?

[slava]

I did an application with a system tray icon and that works fine. However instead of the tray icon itself it is just an empy space in the systray.
I have tryied:

QIcon icon ("Envelop.ico");
trayIcon->setIcon(icon);

QIcon icon ("Envelop.ico");
trayIcon->setIcon(icon);

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but that do nothing. The manual uses an example with some icons in *.svg format but I have only .jpg or .ico. Can I use those and if yes, how? Please help.