Tooltip of system tray icon not shown

Hi, I have a QSystemTrayIcon and I want to set a tool tip for it. This does not work in Windows 7, the tool tip does not appear when I hover over the icon.
I'm using Qt 4.7 and I have tried the supplied "System Tray" example. The tool tip shows up in Windows XP/32bit but not in Windows 7/64bit, just like in my own program.

Any ideas?

Ginsengelf

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Added after 40 minutes:

It looks like it's a known issue:
https://bugreports.qt-project.org/browse/QTBUG-18821
:(