Bug 27764 IResource.findMarkers is called too often
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
if (! (o instanceof IJavaElement))
					return false;
				IJavaElement element= (IJavaElement)o;
				Object resource= element.getAdapter(IResource.class);
				if (! clazz.isInstance(resource))
					return false;
			}
		}
		return true;	
	}
	
	
	
	private void initDragAndDrop() {
		int ops= DND.DROP_COPY | DND.DROP_MOVE | DND.DROP_LINK;
		Transfer[] transfers= new Transfer[] {
			LocalSelectionTransfer.getInstance(), 
			ResourceTransfer.getInstance(),
			FileTransfer.getInstance()};
		
		
		TransferDropTargetListener[] dropListeners= new TransferDropTargetListener[] {
			new SelectionTransferDropAdapter(fViewer),
			new FileTransferDropAdapter(fViewer)
		};
		fViewer.addDropSupport(ops | DND.DROP_DEFAULT, transfers, new DelegatingDropAdapter(dropListeners));
		
		
		Control control= fViewer.getControl();
		TransferDragSourceListener[] dragListeners= new TransferDragSourceListener[] {