Bug 263845 [CommonNavigator] Drag/drop folder from non-Java Proj to Java Proj does copy instead of move sometimes
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDropAdapter.java
*            The viewer this DropAdapter is associated with.
	 */
	public CommonDropAdapter(INavigatorContentService aContentService,
			StructuredViewer aStructuredViewer) {
		super(aStructuredViewer);
		contentService = aContentService;
		dndService = contentService.getDnDService();
		setFeedbackEnabled(false);
	}
	/**
	 * 
	 * @return An array of Transfers allowed by the CommonDropAdapter. Includes
	 *         {@link LocalSelectionTransfer#getTransfer()},
	 *         {@link FileTransfer#getInstance()},
	 *         {@link PluginTransfer#getInstance()}.
	 * @see LocalSelectionTransfer
	 * @see FileTransfer
	 * @see PluginTransfer
	 */
	public Transfer[] getSupportedDropTransfers() {
		return SUPPORTED_DROP_TRANSFERS;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ViewerDropAdapter#dragEnter(org.eclipse.swt.dnd.DropTargetEvent)
	 */
	public void dragEnter(DropTargetEvent event) {
		if (event.detail == DND.DROP_NONE)
			return;