Bug 261506 [CommonNavigator] NavigatorDNDService seems like it can use only interfaces
The NavigatorDNDService class seems like it could use only interface APIs and function properly. Patch attached.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDropAdapter.java
public Object getCurrentTarget() {
		return super.getCurrentTarget();
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.part.PluginDropAdapter#getCurrentTransfer()
	 */
	public TransferData getCurrentTransfer() {
		return super.getCurrentTransfer();
	}
	
    /**
     * Returns the position of the given event's coordinates relative to its target.
     * The position is determined to be before, after, or on the item, based on
     * some threshold value.
     *
     * @param event the event
     * @return one of the <code>LOCATION_* </code>constants defined in this class
     */
    protected int determineLocation(DropTargetEvent event) {
        if (!(event.item instanceof Item)) {
            return LOCATION_NONE;
        }
        Point coordinates = new Point(event.x, event.y);
        coordinates = getViewer().getControl().toControl(coordinates);
        return LOCATION_ON;
    }
}