Bug 167323 [Viewers]Open AbstractTreeViewer for external widget implementors
As reported by Ross Camara AbstractTreeViewer would work for nebula if we would open the API a bit. Boris and I decided that we will do this in 2 steps: 1. open the API 2. moving the Virtual-Support bits from TreeViewer to AbstractTreeViewer when the nebula grid provides virtual support.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
private Object element;
		private Item item;
		UpdateItemSafeRunnable(Item item, Object element) {
			this.item = item;
			this.element = element;
		}
		public void run() {
			doUpdateItem(item, element);
		}