Maybe it is better then to make desktop widget instead of transparent window. It might be impossible to do transparent window in Maemo...

E: Found this: http://doc.qt.nokia.com/qt-maemo-4.6...es-maemo5.html

The Qt::WA_TranslucentBackground window attribute does not work with the current Maemo 5 compositing window manager. All transparent areas are filled with black. An exception are homescreen widgets, whose semi-transparent areas are correctly composited with the home screen.