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
filters = null;
			refresh();
		}
	}
	/**
	 * Ensures that the given element is visible, scrolling the viewer if
	 * necessary. The selection is unchanged.
	 * 
	 * @param element
	 *            the element to reveal
	 */
	public abstract void reveal(Object element);
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.jface.viewers.ContentViewer#setContentProvider(org.eclipse.jface.viewers.IContentProvider)
	 */
	public void setContentProvider(IContentProvider provider) {
		Assert.isTrue(provider instanceof IStructuredContentProvider);
		super.setContentProvider(provider);
	}
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.jface.viewers.Viewer#setInput(java.lang.Object)
	 */
	public final void setInput(Object input) {
		try {
			
			unmapAllElements();
			super.setInput(input);
		} finally {