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
* 
	 * @return non-negative level, or <code>ALL_LEVELS</code> if all levels of
	 *         the tree are expanded automatically
	 * @see #setAutoExpandLevel
	 */
	public int getAutoExpandLevel() {
		return expandToLevel;
	}
	/**
	 * Returns the SWT child items for the given SWT widget.
	 * 
	 * @param widget
	 *            the widget
	 * @return the child items
	 */
	protected abstract Item[] getChildren(Widget widget);
	/**
	 * Get the child for the widget at index. Note that the default
	 * implementation is not very effecient and should be overridden if this
	 * class is implemented.
	 * 
	 * @param widget
	 *            the widget to check
	 * @param index
	 *            the index of the widget
	 * @return Item or <code>null</code> if widget is not a type that can
	 *         contain items.
	 * 
	 * @throws ArrayIndexOutOfBoundsException
	 *             if the index is not valid.