Thanks to some great work by Sam Magnuson, QSystemTrayIcon::showMessage() will support Growl on the mac in Qt 4.3. With this change, supportsMessages() no longer returns false on any of our desktop platforms. Here’s the obligatory screenshot:
Note that the documentation for showMessage() states that messages are not guaranteed to be displayed. As a result, we have received a few requests for an API to query the position of the tray icon (and hence make it possible to popup custom balloons). The awesome news is that for Qt 4.3, we have added QSystemTrayIcon::geometry() that will return the geometry of the icon in global coordinates.