Bug 154064 Need a way to access the TreeItem or TableItem on a refresh
It is not currently possible to know when an item is refreshed. This is required for ownerDraw support in viewers.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
* </p>
	 * 
	 * @param point
	 *            the point in the viewer where you need to corresponding cell
	 *            from
	 * @param onlyInSelection
	 *            search only in selection
	 * @return the cell or if no cell is found at this point
	 */
	ViewerCell getCell(Point point) {
		ViewerRow row = getRowPart(point);
		if (row != null) {
			return row.getCell(point);
		}
		return null;
	}
	/**
	 * Get the ViewerRow at point.
	 * 
	 * @param point
	 * @return ViewerRow
	 */
	protected ViewerRow getRowPart(Point point) {
		Item item = getItem(point.x, point.y);
		if (item != null) {
			return getRowPartFromItem(item);
		}
		return null;
	}
	protected ViewerRow getRowPartFromItem(Widget item) {