rem: var flavourSet = aDragDropObserver.getSupportedFlavours(); for (var flavour in flavourSet.flavourTable) 
add: if (this.mDragSession.isDataFlavorSupported(flavour)) 
context:   dragOver: function (aEvent, aDragDropObserver)    {       if (!("onDragOver" in aDragDropObserver))         return;      if (!this.mDragSession)         this.mDragSession = this.mDragService.getCurrentSession();      if (this.mDragSession)        {          var flavourSet = aDragDropObserver.getSupportedFlavours();          for (var flavour in flavourSet.flavourTable)            {              if (this.mDragSession.isDataFlavorSupported(flavour))                {                  this.mDragSession.canDrop = (this.mDragSession.sourceNode != aEvent.target);                  aDragDropObserver.onDragOver(aEvent,                                                flavourSet.flavourTable[flavour],                                                this.mDragSession);                  aEvent.preventBubble();                  break;                }            }        }    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/73984e3294b2bb7076551497238f998de25ec5a4/nsDragAndDrop.js/clean/xpfe/global/resources/content/nsDragAndDrop.js