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
* </p>
	 * 
	 * @param element
	 *            the element
	 * @return the corresponding widget, or <code>null</code> if none
	 */
	protected final Widget findItem(Object element) {
		Widget result = doFindInputItem(element);
		if (result != null)
			return result;
		
		if (elementMap != null)
			return (Widget) elementMap.get(element);
		return doFindItem(element);
	}
	/**
	 * Notifies any double-click listeners that a double-click has been
	 * received. Only listeners registered at the time this method is called are
	 * notified.
	 * 
	 * @param event
	 *            a double-click event
	 * 
	 * @see IDoubleClickListener#doubleClick
	 */
	protected void fireDoubleClick(final DoubleClickEvent event) {
		Object[] listeners = doubleClickListeners.getListeners();
		for (int i = 0; i < listeners.length; ++i) {
			final IDoubleClickListener l = (IDoubleClickListener) listeners[i];
			Platform.run(new SafeRunnable() {