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/TreeViewer.java
* <strong>EXPERIMENTAL</strong>. This class or interface has been added as
	 * part of a work in progress. There is no guarantee that this API will
	 * remain unchanged during the 3.2 release cycle. Please do not use this API
	 * without consulting with the Platform/UI team.
	 * </p>
	 * 
	 * @since 3.2
	 */
	public void setChildCount(Object element, int count) {
		Tree tree = (Tree) doFindInputItem(element);
		if (tree != null) {
			tree.setItemCount(count);
			return;
		}
		Widget[] items = findItems(element);
		for (int i = 0; i < items.length; i++) {
			TreeItem treeItem = (TreeItem) items[i];
			treeItem.setItemCount(count);
		}
	}
	/**
	 * For a TreeViewer with a tree with the VIRTUAL style bit set, replace the
	 * given parent's child at index with the given element. If the given parent
	 * is this viewer's input, this will replace the root element at the given
	 * index.
	 * <p>
	 * This method should be called by implementers of ILazyTreeContentProvider
	 * to populate this viewer.
	 * </p>
	 *