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
/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected void setSelection(List items) {
		Item[] current = getSelection(getTree());
		
		if (isSameSelection(items, current)) {
			return;
		}
		TreeItem[] newItems = new TreeItem[items.size()];
		items.toArray(newItems);
		getTree().setSelection(newItems);
	}
	/**
	 * Returns <code>true</code> if the given list and array of items refer to
	 * the same model elements. Order is unimportant.
	 * 
	 * @param items
	 *            the list of items
	 * @param current
	 *            the array of items
	 * @return <code>true</code> if the refer to the same elements,
	 *         <code>false</code> otherwise
	 * 
	 * @since 3.1
	 */
	protected boolean isSameSelection(List items, Item[] current) {
		
		int n = items.size();
		if (n != current.length) {