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
* Subclasses do not typically override this method, but implement
	 * <code>setSelectionToWidget(List, boolean)</code> instead.
	 * 
	 * @param selection
	 *            an IStructuredSelection of elements
	 * @param reveal
	 *            <code>true</code> to reveal the first element in the
	 *            selection, or <code>false</code> otherwise
	 */
	protected void setSelectionToWidget(ISelection selection, boolean reveal) {
		if (selection instanceof IStructuredSelection)
			setSelectionToWidget(((IStructuredSelection) selection).toList(), reveal);
		else
			setSelectionToWidget((List) null, reveal);
	}
	/**
	 * Sets this viewer's sorter and triggers refiltering and resorting of this
	 * viewer's element. Passing <code>null</code> turns sorting off.
	 * 
	 * @param sorter
	 *            a viewer sorter, or <code>null</code> if none
	 */
	public void setSorter(ViewerSorter sorter) {
		if (this.sorter != sorter) {
			this.sorter = sorter;
			refresh();
		}
	}
	/**
	 * Configures whether this structured viewer uses an internal hash table to