Bug 232777 [Viewers] ViewerDropAdapter holds currentTarget forever
Build ID: 3.3.2 Member currentTarget should be set to null after drop or after cancel, because it holds a domain object, which can't be garbage collected after Viewer.setInput(null).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerDropAdapter.java
* which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.viewers;
import org.eclipse.core.runtime.Assert;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Item;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.TreeItem;
/**
 * This adapter class provides generic drag-and-drop support for a viewer.
 * <p>
 * Subclasses must implement the following methods:
 * <ul>
 *   <li><code>validateDrop</code> - identifies valid drop targets in viewer</li>
 *   <li><code>performDrop</code> - carries out a drop into a viewer</li>
 * </ul>
 * The <code>setFeedbackEnabled</code> method can be called to turn on and off 
 * visual insertion feedback (on by default).
 * </p>
 */
public abstract class ViewerDropAdapter extends DropTargetAdapter {