Bug 82240 [Viewers] Need a content provider for tables that gets elements lazily
Currently all of our viewers assume that all of the elements are avialble. In the case of a virtual table we also want to be able to load elements as they become visible rather than all at once (common issue for databases). Here are some of the issues 1) Need to setItemCount on the table from the content provider 2) Need a getElements(start,finish) method on the content provider 3) Need to decide how to handle staleness. If there are a million items and the viewer just sits there scrolled to the bottom that is a million TableItems and a million Objects represented. How do we manage memory for this?
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* Specifing <code>properties</code> as <code>null</code> forces a full
	 * update of the element.
	 * </p>
	 * <p>
	 * If the viewer has a sorter which is affected by a change to one of the
	 * properties, the element's position is updated to maintain the sort order.
	 * </p>
	 * <p>
	 * If the viewer has a filter which is affected by a change to one of the
	 * properties, the element may appear or disappear if the change affects
	 * whether or not the element is filtered out.
	 * </p>
	 * 
	 * @param element
	 *            the element
	 * @param properties
	 *            the properties that have changed, or <code>null</code> to
	 *            indicate unknown
	 */
	public void update(Object element, String[] properties) {
		Assert.isNotNull(element);
		Widget item = findItem(element);
		if (item == null)
			return;
		internalUpdate(item, element, properties);
	}
	/**
     * XXX: temporary API in support of Dirk's explorations
     * into grouping by working sets, which requires viewers
     * to support multiple equal elements.