Bug 186025 [Viewers] Virtual Manager should be cleared when Viewer is disposed
Got a nasty memory leak where the Workbench would keep my disposed viewer in a field since it was registered as a selection provider. In StructuredViewer#handleDisposed(), the input is set to null, however this does not clear a possible virtual manager being used from the Table Viewer. The Table Viewer should clear the cache of the virtual manager on handleDispose to make sure, no reference to any model object is retained.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTableViewer.java
*/
	protected abstract void doShowItem(Item item);
	/**
	 * Deselects all selected items in the receiver.
	 *
	 * @since 3.3
	 */
	protected abstract void doDeselectAll();
	/**
	 * Sets the receiver's selection to be the given array of items. The current
	 * selection is cleared before the new items are selected.
	 * <p>
	 * Items that are not in the receiver are ignored. If the receiver is
	 * single-select and multiple items are specified, then all items are
	 * ignored.
	 * </p>
	 *
	 * @param items
	 *            the array of items
	 *
	 * @exception IllegalArgumentException -
	 *                if the array of items is null
	 *
	 * @since 3.3
	 */
	protected abstract void doSetSelection(Item[] items);
	/**
	 * Shows the selection. If the selection is already showing in the receiver,
	 * this method simply returns. Otherwise, the items are scrolled until the
	 * selection is visible.