Bug 156537 [Viewers] Virtual tree viewer does not populate with initial children
I20060830-1650 When a tree viewer is created with the SWT.Vitrual flag and uses an ILazyTreeContentProvider, the viewew does not populate with the initial children in the model. The method TreeViewer.createChildren(Widget) only updates existing items if the parent (root)element has been mapped to data, and does not query the content provider for the number of children it has. Attached is a sample plug-in showing the problem. The tree "model" looks like this: root one two three When the input is set to the viewer ("root") a call is made to "createChildren", but the content provider is never used.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*            the control
	 * @return the number of children
	 */
	protected abstract int getItemCount(Control control);
	/**
	 * Returns the number of child items of the given SWT item.
	 * 
	 * @param item
	 *            the item
	 * @return the number of children
	 */
	protected abstract int getItemCount(Item item);
	/**
	 * Returns the child items of the given SWT item.
	 * 
	 * @param item
	 *            the item
	 * @return the child items
	 */
	protected abstract Item[] getItems(Item item);
	/**
	 * Returns the item after the given item in the tree, or <code>null</code>
	 * if there is no next item.
	 * 
	 * @param item
	 *            the item
	 * @param includeChildren
	 *            <code>true</code> if the children are considered in
	 *            determining which item is next, and <code>false</code> if
	 *            subtrees are ignored