What is the use of the Qt::Desktop window flag?
The "documentation":http://doc.qt.nokia.com/stable/qt.html shows:
Qt::Desktop 0x00000010 | Window Indicates that this widget is the desktop. This is the type for QDesktopWidget.
Other flags in the same series tell the WM what type of window it is dealing with: does this flag turn the window into the desktop? (That sounds not really probable). What else would you use this flag for then?
There is a special widget called "QDesktopWidget":http://doc.qt.nokia.com/latest/qdesktopwidget.html, which allows for accessing screen information on multi-head systems. You cannot use it directly and you will have to use QApplication::desktop() to retrieve it.
The Qt::Desktop flag is (at least as far as I know) used internally only to distinguish the QDesktopWidget from other widgets and is not passed to any window manager.