Bug 213166 [Viewers] Problems with OwnerDrawLabelProvider.setUpOwnerDraw
3.4 M4 To set up the owner draw callbacks for a viewer OwnerDrawLabelProvider.setUpOwnerDraw is offered. The problem of this is: a. there's no way to uninstall the callbacks. In our views we want to allow to enable and disable owner draw in the preferences b. from an API client perspective, it would be nicer if the label provider could install itself when installed. A good solution would be to add more life cycle to a label provider. CellLabelProvider.initialize(ColumnViewer, int column) There's already ILableProvider.dispose when a label provider is removed from a viewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ContentViewer.java
* <li>
 * create SWT controls for viewer (in constructor) (optional)
 * </li>
 * <li>
 * initialize SWT controls from input (inputChanged)
 * </li>
 * <li>
 * define viewer-specific update methods
 * </li>
 * <li>
 * support selections (<code>setSelection</code>, <code>getSelection</code>)
 * </ul>
 * </p>
 */
public abstract class ContentViewer extends Viewer {
    /**
     * This viewer's content provider, or <code>null</code> if none.
     */
    private IContentProvider contentProvider = null;
    /**
     * This viewer's input, or <code>null</code> if none.
     * The viewer's input provides the "model" for the viewer's content.
     */
    private Object input = null;
    /**
     * This viewer's label provider. Initially <code>null</code>, but
     * lazily initialized (to a <code>SimpleLabelProvider</code>).
     */
    private IBaseLabelProvider labelProvider = null;
    /**