Bug 161086 [Viewers] performance problem in AbstractTreeViewer.internalExpandToLevel
If you expand to ALL_LEVELS, internalExpandToLevel will call createChildren even if the element has no children, i.e. it does not check if the element is expandable. Found this while experimenting with the Quick Access feature (enter "con", then delete all three characters one at a time).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
}
		Item[] items = getChildren(getControl());
		if (items != null) {
			for (int i = 0; i < items.length; i++) {
				Widget o = internalFindItem(items[i], element);
				if (o != null) {
					return o;
				}
			}
		}
		return null;
	}
	/**
	 * Copies the attributes of the given element into the given SWT item.
	 * 
	 * @param item
	 *            the SWT item
	 * @param element
	 *            the element
	 */
	protected abstract void doUpdateItem(Item item, Object element);
	
	protected void doUpdateItem(Widget widget, Object element, boolean fullMap) {
		if (widget instanceof Item) {
			Item item = (Item) widget;
			
			if (fullMap) {
				associate(element, item);
			} else {
				Object data = item.getData();