PySide.QtGui.QIconDragEvent class indicates that a main icon drag has begun.
Icon drag events are sent to widgets when the main icon of a window has been dragged away. On Mac OS X, this happens when the proxy icon of a window is dragged off the title bar.
It is normal to begin using drag and drop in response to this event.
构造图标拖曳事件对象，并将接受标志设为 false。
另请参阅
PySide.QtCore.QEvent.accept()
