Bug 174701 [Viewers] ViewerRow should be reused instead of connected to the Item
Currently we create a ViewerRow ver every Item we create this can degrade performance, we should cache the row and reuse it
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*            the element
	 * @return whether the given element is expandable
	 */
	private boolean isExpandable(Item item, TreePath parentPath, Object element) {
		Object elementOrTreePath = element;
		if (isTreePathContentProvider()) {
			if (parentPath != null) {
				elementOrTreePath = parentPath.createChildPath(element);
			} else {
				elementOrTreePath = getTreePathFromItem(item);
			}
		}
		return isExpandable(elementOrTreePath);
	}
	
	protected void labelProviderChanged() {
		
		Control tree = getControl();
		tree.setRedraw(false);
		
		internalRefresh(tree, getRoot(), false, true);
		tree.setRedraw(true);
	}
	/**
	 * Creates a new item.
	 * 
	 * @param parent
	 *            the parent widget
	 * @param style
	 *            SWT style bits