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
/**
	 * Adds support for dropping items into this viewer via a user drag-and-drop
	 * operation.
	 * 
	 * @param operations
	 *            a bitwise OR of the supported drag and drop operation types (
	 *            <code>DROP_COPY</code>,<code>DROP_LINK</code>, and
	 *            <code>DROP_MOVE</code>)
	 * @param transferTypes
	 *            the transfer types that are supported by the drop operation
	 * @param listener
	 *            the callback that will be invoked after the drag and drop
	 *            operation finishes
	 * @see org.eclipse.swt.dnd.DND
	 */
	public void addDropSupport(int operations, Transfer[] transferTypes,
			final DropTargetListener listener) {
		Control control = getControl();
		DropTarget dropTarget = new DropTarget(control, operations);
		dropTarget.setTransfer(transferTypes);
		dropTarget.addDropListener(listener);
	}
	/**
	 * Adds the given filter to this viewer, and triggers refiltering and
	 * resorting of the elements.
	 * 
	 * @param filter
	 *            a viewer filter
	 */
	public void addFilter(ViewerFilter filter) {